Metal-based structure or nanoparticles containing hydrogen, and method for producing same

ABSTRACT

To provide a metal-based structure or nanoparticles whose homogeneity is not deteriorated and whose sticking formation is easy, and a production method thereof with a high safety. A metal-based structure comprises a hydrogen compound, cluster, or an aggregate thereof, represented by the general formula: MmH. The M is a metal-based atom. The m is an integer of 3 or more and 300 or less. H is a hydrogen atom.

TECHNICAL FIELD

The present invention relates to a metal-based structure ornanoparticles containing hydrogen, and a method for producing the same.

BACKGROUND ART

A metal-based structure, which is a structure in which multiplemetal-based powder bodies having a particle size of less than 1 μm,preferably 500 nm or less, more preferably 300 nm (which may sometimesbe referred to as the “nanoparticle” herein) approach each other,whereby they are stuck to each other to form a pre-determined shapecharacteristic, is a promising material having excellent mechanicalproperties and chemical properties.

The metal-based structure can be usually obtained by sintering thenanoparticle in a pressurized environment, as described in Non PatentLiterature 1, and the like. In general, the temperature necessary forsintering particles falls as the particle size of the powder isdecreased, and thus it is preferable to use the nanoparticles as thepowder for sintering in the terms of the increase of productivity when astructure is produced by the sintering.

CITATION LIST Non Patent Literature

-   Non Patent Literature 1: “Powder and Powder Metallurgy” vol. 38, 7,    pages 854-857 (Japanese)

SUMMARY OF INVENTION Technical Problem

The nanoparticles, however, have a larger surface area per unit masscompared that of particles having a particle size of micron size or more(hereinafter referred to as “non-nanoparticles”), and thus they areeasily reacted with oxygen in the air, and the reaction of thenanoparticles with oxygen may be explosively advanced. For thosereasons, the handling thereof is difficult, and the facility charge forsecuring the safety of the sintering work is large.

Even if the sintering is performed while the attention is paid so thatthe reaction with oxygen is not explosively advanced, an amount ofsubstances adsorbing the nanoparticles used for the sintering isremarkably larger than that in the non-nanoparticles. For that reason,when the sintering is performed using the nanoparticles, though thesintering temperature itself is low, the obtained metal-based structurehas a large content of impurities derived from the adsorptionsubstances, and there may be cavities, formed by volatilization ordecomposition of the impurities, inside the metal-based structure. Bythe inclusion of the impurities and the existence of cavities, thehomogeneity of the metal-based structure is deteriorated and themechanical properties and chemical properties are deteriorated.Consequently, almost all of the metal-based structures producedaccording to the prior art are inferior to metal-based structurestheoretically expected.

Furthermore, conventional metal nanoparticles have an oxidized layer,and thus a reduction operation or a pressurization operation isnecessary in order to adhere particles to each other, and the formationof nanostructure is very difficult.

As explained above, when the sintering is performed using theconventional metal nanoparticles, it is not easy to secure the safety,the obtained metal-based structure has easily the deterioratedhomogeneity, and the adherence formation is difficult. A method forindustrially producing a metal-based structure having no problemsdescribed above, accordingly, has been desired.

In view of the circumstance described above, the present invention aimsat providing a metal-based structure or nanoparticles, which do not havethe deteriorated homogeneity and are easy to adhere to each other, and amethod for producing the same with a high safety.

Solution to Problem

The present inventions, which are provided for solving the problemsdescribed above, are as follows:

(1) A metal-based structure comprising a hydrogen compound, a cluster,or an aggregate thereof, represented by the general formula: M_(m)H

wherein

M is a metal-based atom;

m is an integer of 3 or more and 300 or less; and

H is a hydrogen atom.

(2) The metal-based structure according to item (1), wherein the M is ametal atom, and the m is any of 4, 6, 8, 12, 20, or 30.(3) A metal-based structure comprising a metal-based amorphous phasewhich is amorphized by containing hydrogen.(4) A metal-based structure which contains hydrogen, wherein a content Aof the hydrogen, % by atom, is a value satisfying the following formulae(1) and (2), based on the whole amount of the metal-based structure.

Y=100×1/(X+1) wherein X=4,6,8,12,20, or 30   (1)

0.85Y≤A≤1.15Y  (2)

(5) The metal-based structure according to any of items (1) to (4),wherein at least a part of the hydrogen are non-diffusible hydrogenwhich is contained in the metal-based structure after the metal-basedstructure is heated at 200° C. for 2 minutes.(6) A metal-based structure which contains hydrogen, wherein at least apart of the hydrogen are non-diffusible hydrogen contained in themetal-based structure after the metal-based structure is heated at 200°C. for 2 minutes, and a content of the non-diffusible hydrogen is 0.01%by mass or more, or 0.41% by atom or more, based on the whole amount ofthe metal-based structure.(7) A metal-based structure which contains hydrogen, wherein a contentof the hydrogen is 0.095% by mass or more, or 5.04% by atom or more,based on the whole amount of the structure.(8) The metal-based structure according to any of items (1) to (7),wherein the metal-based structure comprises an amorphous phase at leastin part.(9) The metal-based structure according to item (8), wherein theamorphous phase contains hydrogen.(10) A metal-based structure which comprises a metal-based amorphousphase containing hydrogen, wherein

a content of the hydrogen, after the metal-based structure is heated at200° C. for 2 minutes, is 0.01% by mass or more, or 0.41% by atom ormore, based on the whole amount of the metal-based structure.

(11) The metal-based structure according to any of items (3), (6), or(10), wherein the hydrogen content is 0.037% by mass or more and 0.59%by mass or less, or 2.0% by atom or more and 25% by atom or less, basedon the whole amount of the metal-based structure.(12) The metal-based structure according to any of items (1) to (11),wherein

the metal-based structure is a metal-based structure comprising a metalas a main component, and

the metal is a ferromagnetic substance.

(13) The metal-based structure according to any of items (1) to (12),wherein the metal-based structure comprises a metal element as a maincomponent.(14) The metal-based structure according to item (13), wherein the metalelement comprises a single element.(15) The metal-based structure according to any of items (1) to (14),wherein the metal-based structure contains iron.(16) The metal-based structure according to any of items (1) to (15),wherein at least a part of the metal-based structure comprises aparticle structure.(17) The metal-based structure according to any of items (1) to (16),wherein at least a part of the metal-based structure comprises awire-shaped structure.(18) The metal-based structure according to any of items (1) to (17),wherein the metal-based structure comprises a formless, amorphous phase,which fills up a cavity in the metal-based structure, or consists of theformless, amorphous phase.(19) The metal-based structure according to item (16) or (17), whereinthe particle structure or the wire-shaped structure is formed by aself-granulating reaction.(20) The metal-based structure according to any of items (1) to (19),wherein

the metal-based structure comprises a hydrogen compound, a cluster, oran aggregate thereof, which comprises a regular polyhedron structure oran almost regular polyhedron structure, and

in the regular polyhedron structure, a metal atom is disposed on eachvertex of the regular polyhedron structure, or on the middle of eachsurface or each side, centered on a hydrogen atom.

(21) A metal-based structure, which is a metal-based structure boundbody of a metal-based structure according to any of items (1) to (20),wherein the metal-based structure bound body comprises a shapeanisotropy.(22) The metal-based structure or the metal-based structure bound bodyaccording to any of items (1) to (21), which is used for a 3D printer.(23) A method for producing a metal-based structure, which is astructure obtained by reducing a reducible substance which is asubstance containing a metal-based reducible component containing atleast one metal element and/or semi-metal element, comprising a step ofcontrolling at least one of the following (i) to (iii) by controlling ahydrogen content based on the whole amount of the metal-based structure,the hydrogen being contained in the metal-based structure:

(i) controlling formation of an amorphous phase which the metal-basedstructure comprises;

(ii) controlling a particle shape of the metal-based structure; and

(iii) controlling a composition of the metal-based structure.

(24) A method for producing a metal-based structure according to any oneof items (1) to (22), which is a method for producing a metal-basedstructure, which is a structure obtained by reducing, in liquid, areducible substance which is a substance containing a metal-basedreducible component containing at least one metal element and/orsemi-metal element, comprising a step of controlling at least one of thefollowing (i) to (iii) by controlling a hydrogen content based on thewhole amount of the metal-based structure, the hydrogen being containedin the metal-based structure:

(i) controlling formation of an amorphous phase which the metal-basedstructure comprises;

(ii) controlling a particle shape of the metal-based structure; and

(iii) controlling a composition of the metal-based structure.

(25) The method for producing a metal-based structure according to items(23) or (24), wherein

the hydrogen content is controlled to 0.41% by atom or more, thereby toform the metal-based structure comprising a metal-based amorphous phaseand/or,

the hydrogen content is controlled to 2.0% by atom or more, thereby toform the metal-based structure comprising a metal-based amorphous phasewherein the metal-based amorphous phase comprises a metal element as amain component and/or,

the hydrogen content is controlled to 3.3% by atom or more, thereby toform the metal-based structure substantially comprising a metal-basedamorphous phase alone wherein the metal-based amorphous phase comprisesa metal element as a main component and/or,

the hydrogen content is controlled to 5.5% by atom or more, thereby toform the metal-based structure substantially comprising a metal-basedamorphous phase alone wherein the metal-based amorphous phase comprisesa metal element as a main component and a least a part of themetal-based amorphous phase is formless.

(26) The method for producing a metal-based structure according to anyof items (23) to (25), wherein the hydrogen content is controlled to0.41% by atom or more and 13% by atom or less, thereby to control anaverage length of a particle structure or an average short axis lengthof a wire-shaped structure of the metal-based structure to 500 nm orless.(27) The method for producing a metal-based structure according to anyof items (23) to (26), wherein

the A % by atom, which is the hydrogen content, is controlled to a valuesatisfying the following formulae (1) and (2) based on the whole amountof the metal-based structure.

Y=100×1/(X+1) wherein X=4,6,8,12,20, or 30  (1)

0.85Y≤A≤1.15Y  (2)

(28) A method for producing a metal-based structure which comprises ahydrogen compound, a cluster, or an aggregate thereof, represented bythe general formula: M_(m)H

wherein

M is a metal-based atom;

m is an integer of 3 or more and 300 or less; and

H is a hydrogen atom,

the method comprising a step of:

controlling the m to 30 or less, whereby the metal-based structurecomprises a metal element as a main component and/or,

controlling the m to 31 or more, whereby the metal-based structurecomprises a metal as a main component.

(29) A method for producing a metal-based structure which comprises ahydrogen compound, a cluster, or an aggregate thereof, represented bythe general formula: M_(m)H

wherein

M is a metal-based atom;

m is an integer of 3 or more and 300 or less; and

H is a hydrogen atom,

the method comprising a step of:

controlling the m to 31 or more, thereby to form the metal-basedstructure comprising a metal-based amorphous phase and/or,

controlling the m to 30 or less, thereby to form the metal-basedstructure comprising a metal-based amorphous phase wherein themetal-based amorphous phase comprises a metal element as a maincomponent and/or,

controlling the m to 20 or less, thereby to form the metal-basedstructure substantially comprising a metal-based amorphous phase alonewherein the metal-based amorphous phase comprises a metal element as amain component and/or,

controlling the m to 12 or less, thereby to form the metal-basedstructure substantially comprising a metal-based amorphous phase alonewherein the metal-based amorphous phase comprises a metal element as amain component and at least a part of the metal-based amorphous phase isformless.

(30) The method for producing a metal-based structure according to item(28) or (29), wherein the m is controlled to 8 or more, thereby tocontrol an average length of a particle structure or an average shortaxis length of a wire-shaped structure of the metal-based structure to500 nm or less.(31) The method for producing a metal-based structure according to anyof items (23) to (30), wherein

at least a part of hydrogen contained in the metal-based structure arenon-diffusible hydrogen contained in the metal-based structure after themetal-based structure is heated at 200° C. for 2 minutes.

(32) A method for producing a metal-based structure which containshydrogen, comprising a step of a reduction step which comprises reducinga reducible substance containing at least one of a metal element and/ora semi-metal element in liquid containing at least one of hydrogen and ahydrogen-containing substance, wherein

at least a part of the hydrogen are non-diffusible hydrogen contained inthe metal-based structure after the metal-based structure is heated at200° C. for 2 minutes.

(33) The method for producing a metal-based structure according to item(32), wherein the reduction step comprises a step in which a solution Awhich contains a reducible substance containing at least one of a metalelement and/or a semi-metal element and a solution B which contains atleast one of hydrogen and a hydrogen-containing substance, and has areducing action are mixed to form mixed liquid.(34) The method for producing a metal-based structure according to item(33), wherein

the metal-based structure comprises a hydrogen compound, a cluster, oran aggregate thereof, represented by the general formula: M_(m)H

wherein

M is a metal-based atom;

m is an integer of 3 or more and 300 or less;

H is a hydrogen atom, and

a concentration of the reducible substance in the solution A iscontrolled to a threshold value T mmol/kg or more, thereby to adjust them to 30 or less.

(35) The method for producing a metal-based structure according to item(33), wherein

a concentration of the reducible substance in the solution A is adjustedto less than a threshold value T mmol/kg, and a concentration of thehydrogen or the hydrogen-containing substance in the solution B isadjusted to 6 mmol/kg or more, thereby to adjust a content of thehydrogen to less than 2.0% by atom based on the whole amount of themetal-based structure and/or,

a concentration of the reducible substance is adjusted to the thresholdvalue T mmol/kg or more and a concentration of the hydrogen or thehydrogen-containing substance is adjusted to 6 mmol/kg or more, therebyto adjust a content of the hydrogen to 2.0% by atom or more, and

the threshold value T is 3.

(36) The method for producing a metal-based structure according to item(34) or (35), wherein

an alcohol is added to a solvent in the solution A and/or the solution Bin an amount of 1% by mass or more based on the whole amount of thesolvent to which the alcohol is added, whereby the threshold value Tmmol/kg becomes lower compared to the case in which the alcohol is notadded.

(37) The method for producing a metal-based structure according to item(33), wherein

a concentration of the reducible substance in the solution A is adjustedto 0.3 mmol/kg or more and a concentration of the hydrogen and thehydrogen-containing substance in the solution B is adjusted to 6 mmol/kgor more, whereby the metal-based structure is formed into a metal-basedstructure comprising a hydrogen compound, a cluster, or an aggregatethereof, represented by the general formula: M_(m)H wherein M is a metalatom; m is any of 4, 6, 8, 12, 20, or 30; and H is a hydrogen atom.

(38) The method for producing a metal-based structure according to anyof items (33) to (37), which further comprises a step in which amagnetic field is applied to the mixed liquid, thereby to control ashape anisotropy of the metal-based structure.(39) A method for producing a metal-based structure comprising a step ofapplying a magnetic field to a metal-based structure according to any ofitems (1) to (22), thereby to control a shape anisotropy of themetal-based structure.(40) A method for producing a metal-based structure comprising a step ofimparting an additional substance to a cavity in a metal-based structureaccording to any of items (1) to (22).(41) A method for producing a metal-based structure comprising a step ofheating and/or pressurizing a metal-based structure according to any ofitems (1) to (22), thereby to decrease a volume of a cavity in themetal-based structure, to stick the metal-based structures to eachother, to stick the part structures in the metal-based structure to eachother, and/or to stick an additional substance to the metal-basedstructure.(42) A method for producing a metal-based structure, comprising a stepof heating a metal-based structure according to any of items (1) to(22), thereby to form a crystal phase at least in part.

Advantageous Effects of Invention

According to the present invention, a metal-based structure ornanoparticles, which do not have the deteriorated homogeneity and areeasy to adhere to each other, and a method for producing the same with ahigh safety are provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically showing dependency of the shape of ametal-based structure, produced by a production method according to oneembodiment of the present invention, on a concentration of a startingmaterial and a magnetic field strength for the solidification.

FIG. 2 is an image showing one example of a metal-based structureaccording to Example 1-1.

FIG. 3 is an image showing another example of a metal-based structureaccording to Example 1-1.

FIG. 4 is an image showing still another example of a metal-basedstructure according to Example 1-1.

FIG. 5 is an image showing a still further example of a metal-basedstructure according to Example 1-1.

FIG. 6 is an image showing one example of a metal-based structureaccording to Example 1-2.

FIG. 7 is an image showing one example of a metal-based structureaccording to Example 1-3.

FIG. 8 is an image showing one example of a metal-based structureaccording to Example 1-4.

FIG. 9 is an image showing another example of a metal-based structureaccording to Example 1-4.

FIG. 10 is an image showing one example of a metal-based structureaccording to Example 1-4-2.

FIG. 11 is an image showing another example of a metal-based structureaccording to Example 1-4-2.

FIG. 12 is an image showing one example of a metal-based structureaccording to Example 1-4-3.

FIG. 13 is an image showing another example of a metal-based structureaccording to Example 1-4-3.

FIG. 14 is an image showing still another example of a metal-basedstructure according to Example 1-4-3.

FIG. 15 is an image showing a still further example of a metal-basedstructure according to Example 1-4-3.

FIG. 16 is an image showing one example of a metal-based structureaccording to Example 1-5.

FIG. 17 is an image showing one example of a metal-based structureaccording to Example 1-6.

FIG. 18 is an image showing one example of a metal-based structureaccording to Example 1-7.

FIG. 19 is an image showing another example of a metal-based structureaccording to Example 1-7.

FIG. 20 is an image showing still another example of a metal-basedstructure according to Example 1-7.

FIG. 21 is an image showing a still further example of a metal-basedstructure according to Example 1-7.

FIG. 22 is an image showing one example of a metal-based structureaccording to Example 1-7-1.

FIG. 23 is an image showing one example of a metal-based structureaccording to Example 1-7-3.

FIG. 24 is an image showing one example of a metal-based structureaccording to Example 1-7-4.

FIG. 25 is an image showing another example of a metal-based structureaccording to Example 1-7-4.

FIG. 26 is an image showing one example of a metal-based structureaccording to Example 1-8.

FIG. 27 is an image showing one example of a metal-based structureaccording to Example 1-9.

FIG. 28 is an image showing one example of a metal-based structureaccording to Example 1-9-1.

FIG. 29 is an image showing one example of a metal-based structureaccording to Example 1-9-2.

FIG. 30 is an image showing one example of a metal-based structureaccording to Example 1-10.

FIG. 31 is an image showing one example of a metal-based structureaccording to Example 1-11.

FIG. 32 is an image showing another example of a metal-based structureaccording to Example 1-11.

FIG. 33 is an image showing one example of a metal-based structureaccording to Example 1-12.

FIG. 34 is an image showing one example of a metal-based structureaccording to Example 1-12-1.

FIG. 35 is an image showing one example of a metal-based structureaccording to Example 1-12-2.

FIG. 36 is an image showing one example of a metal-based structureaccording to Example 1-13.

FIG. 37 is an image showing another example of a metal-based structureaccording to Example 1-13.

FIG. 38 is an image showing still another example of a metal-basedstructure according to Example 1-13.

FIG. 39 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-1 in Example of the present invention.

FIG. 40 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-4 in Example of the present invention.

FIG. 41 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-4-4 in Example of the presentinvention.

FIG. 42 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-7 in Example of the present invention.

FIG. 43 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-7-5 in Example of the presentinvention.

FIG. 44 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-9 in Example of the present invention.

FIG. 45 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-10 in Example of the present invention.

FIG. 46 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-10-1 in Example of the presentinvention.

FIG. 47 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-11 in Example of the present invention.

FIG. 48 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-11-1 in Example of the presentinvention.

FIG. 49 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-12 in Example of the present invention.

FIG. 50 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-12-2 in Example of the presentinvention.

FIG. 51 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-13 in Example of the present invention.

FIG. 52 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-13-1 in Example of the presentinvention.

FIG. 53 is a view showing a DSC profile of a metal-based structureaccording to Example 1-4-1 in Example of the present invention.

FIG. 54 is a view showing a DSC profile of a metal-based structureaccording to Example 1-7 in Example of the present invention.

FIG. 55 is a view showing a DSC profile of a metal-based structureaccording to Example 1-10 in Example of the present invention.

FIG. 56 is a view showing a DSC profile of a metal-based structureaccording to Example 1-11 in Example of the present invention.

FIG. 57 is a view showing a DSC profile of a metal-based structureaccording to Example 1-12-1 in Example of the present invention.

FIG. 58 is a view showing a DSC profile of a metal-based structureaccording to Example 1-13 in Example of the present invention.

FIG. 59 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 2-3 in Example of the present invention.

FIG. 60 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 2-7 in Example of the present invention.

FIG. 61 is a view schematically showing dependency of a composition of ametal-based structure on a concentration of an aqueous iron sulfatesolution and a concentration of an aqueous reducing agent solution,based on results in Example 2.

FIG. 62 is a view schematically showing dependency of a composition of ametal-based structure on a volume ratio and a concentration of anaqueous reducing agent solution, based on results in Example 2.

FIG. 63 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-9-3 in Example of the presentinvention.

FIG. 64 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-11-4 in Example of the presentinvention.

FIG. 65 is a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-11-5 in Example of the presentinvention.

FIG. 66 a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-14 in Example of the present invention.

FIG. 67 a view showing X-ray diffraction spectra of a metal-basedstructure according to Example 1-14-2 in Example of the presentinvention.

FIG. 68 is an SEM image of a metal-based structure according to Example1-11-3 in Example of the present invention.

FIG. 69 is an SEM image of a metal-based structure according to Example1-11-5 in Example of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are explained.

1. Metal-Based Structure (1-1) Structural Characteristic (1-1-1)Metal-Based Structure or Nanoparticle

In the instant specification, a “metal” refers to a substance formed ofa part of typical elements and transition elements, and a single entitythereof has natures of a metal. A substance can be assumed as a metal ifit has the following natures. It is in the state of a solid at a normaltemperature in a normal pressure (excluding mercury), has spreadabilityand metallic luster, is a good conductor of electricity and heat, andforms a cation (a positive ion) in an aqueous solution. As specificexamples of the “semi-metal”, B, Si, Ge, As, Sb, Te, Se, Po, At, C, andP can be mentioned. The semi-metal has generally natures between a metaland a nonmetal, and Ge, Sb and Po may sometimes be classified into themetals. An “intermetallic compound” refers to a compound combined ofmetals, or a metal and a semi-metal. A “metal compound” refers to acompound containing a metal but excludes the combinations of a metal anda metal, or a metal and a semi-metal.

Specific examples thereof may include metal oxides, metal nitrides, andthe like. Alloys and intermetallic compounds containing a mixture ofmultiple metal elements and semi-metal elements are assumed as one formof metals. The term “metal-based” refers to a material containing, as amain component, a “metal,” but it can contain a non-metal component. The“metal-based structure or nanoparticles” refer to a structure ornanoparticles containing, as a main component, a metal. The “structure”includes “nanoparticles.”

(1-1-2) Hydrogen (which May Sometimes be Described as “H” in the InstantSpecification)-Containing Phase and Amorphous Phase

(1-1-2-1) Characteristics of Metal-Based Structure According to PresentInvention

The metal-based structure according to one embodiment of the presentinvention has at least one characteristic from the following (i) to(iv):

(i) To contain hydrogen atoms in an amount of 0.01% by mass or morebased on the whole amount of the metal-based structure;(ii) To contain hydrogen atoms in an amount of 0.41% by atom or morebased on the whole amount of the metal-based structure;(iii) To contain an amorphous phase; and(iv) The metal-based structure contains an amorphous phase, and X-raydiffraction spectra showing existence of a metal phase are obtained in acondition in which the metal-based structure is heated to becrystallized.

(1-1-2-2) Hydrogen-Content

In the instant specification, the content of the hydrogen atoms in themetal-based structure is measured in accordance with JIS Z 2614. Themeasurement can be performed using an apparatus described in JIS H 1619“Titanium and Titanium Alloy-Determination of Hydrogen Content.”Specifically, it is exemplified by a method in which using an apparatusdescribed in JIS H 1619 “Titanium and Titanium Alloy-Determination ofHydrogen Content-5 Inert Gas Fusion-Thermal Conductivity Method,”hydrogen is measured as it is. One example of specific measurementapparatus may include “EMGA-621A” manufactured by HORIBA Ltd.

The outline of the measurement method can be as follows: A sample isheat-melted together with tin using a graphite crucible in an inert gasstream in an impulse furnace, and hydrogen is extracted with othergases. The extracted gases are passed through a separation column asthey are to separate hydrogen from them, and the hydrogen is introducedinto a thermal conductivity detector, thereby measuring a change of athermal conductivity caused by hydrogen.

A determination method using, as the unit of the hydrogen content, % bymass (in the instant specification, which may sometimes be described as“% by weight”) is simple and effective, when Fe is contained, or aferromagnetic material such as Ni or Co is contained. It is applicableto all of other cases.

On the other hand, the unit % by atom (in the instant specification,which may sometimes be written as “at %”) is effective in a case inwhich more theoretical and essential control is performed, which isrelatively better, in view of the fact that it is possible to performthe control by not only the method described above but also anothermethod (a method in which the number of atoms is directly counted, andthe like). The unit % by mass can be exactly converted into the unit %by atom, if a metal-based structure to be measured is a single phase.However, if the metal-based structure is a diploid phase, the conversioncannot be performed unless the composition ratio thereof is obtained.When the metal-based structure is the diploid phase, the compositionratio thereof is obtained by another method (such as ICP), and then theconversion is performed.

Essentially, it is preferable to perform the control with the unit % byatom, but the unit % by mass may be adopted for simplifying the control.In the instant specification, the unit of the hydrogen content maysometimes be expressed by “H %” including the both.

When the hydrogen content is adjusted to 0.001% by mass or more to thewhole metal-based structure, it is difficult to exert the influence ofoxidation on the metal-based structure, and thus the adherence and thesintering property are excellent. The hydrogen content is morepreferably 0.010% by mass or more, still more preferably 0.20% by massor more, in terms of the more excellent adherence and sinteringproperty.

When the hydrogen content is adjusted to 0.41% by atom or more to thewhole metal-based structure, it is difficult to exert the influence ofoxidation on the metal-based structure, and thus the adherence and thesintering property are excellent. The hydrogen content is morepreferably 5.04% by atom or more, still more preferably 5.5% by atom ormore, in terms of the more excellent adherence and sintering property.

Though the detailed explanation is described below, in general, it isnot easy to form a metal amorphous phase from a reason in which quickcooling is necessary from a melted state, and the like. In particular,it is very difficult to form an amorphous form formed of a high purityof a metal component, or it is further very difficult to form anamorphous form formed of a high purity of a metal element.

In the present invention, the amorphous part or the hydrogen-containingamorphous part can be stably formed or maintained by containing hydrogenin the metal-based structure, and adjusting the hydrogen content to0.41% by atom (0.01% by mass) or more, based on the whole amount of themetal-based structure, preferably 3.03% by atom (0.056% by mass) ormore, more preferably 5.3% by atom (0.10% by mass) or more, still morepreferably 10.1% by atom (0.20% by mass) or more. In addition, when theamorphous part stably exists and the purity of the metal elements in themetal-based structure is stably formed or maintained in thehydrogen-containing metal-based structure or the hydrogen-containingamorphous form, the crystallized metal phase after the heat-treatment orthe high purity of the metal-based structure is effectively produced.

When the metal-based structure contains hydrogen, contains it in acontent equal to or more than a specified value, and/or has theamorphous part, it is possible to produce the metal-based structurewithout containing a nucleating agent, whereby various shapes can beminutely formed, and a high purity can be preferably obtained. Thehydrogen-containing amorphous substance exhibits excellent effects onthe shape control of the metal-based structure, as described below. Theconditions described above are also effective for forming of theformless phase.

The upper limit of the hydrogen content of the metal-based structure isnot particularly limited. It is preferable that the hydrogen content ofthe metal-based structure is preferably 50% by atom or less, morepreferably 25% by atom or less or less than 25% by atom, and there arecases the content is more preferably 23% by atom or less or less than23% by atom, 20% by atom or less or less than 20% by atom, 16.4% by atomor less or less than 16.4% by atom, or 13% by atom or less or less than13% by atom.

Here, the hydrogen contained in the metal-based structure is explainedin detailed. The hydrogen includes diffusible hydrogen andnon-diffusible hydrogen. In general, the diffusible hydrogen refers tohydrogen existing in a material, which goes out (diffuses) from thematerial at room temperature over time. The non-diffusible hydrogenrefers to hydrogen existing in the material, which cannot go out (doesnot diffuse) from the material even at room temperature to about 200° C.over time. It can be considered that the diffusible hydrogen maycontribute to hydrogen embrittlement.

From the above, the hydrogen which does not go out from the metal-basedstructure when the metal-based structure of the present invention isheated at 200° C. for 2 minutes can be said to be the non-diffusiblehydrogen. The hydrogen amount in each state can also be measured using athermal desorption analyzer (TDS). This can be similarly said in anycase when the metal-based structure is in the state of an amorphousphase or a crystallized phase.

The hydrogen content when heating at 200° C. for 2 minutes is adjustedto preferably 0.01% by mass or more or 0.41% by atom or more, based onthe whole amount of the structure, more preferably 0.056% by mass ormore or 3.03% by atom or more, still more preferably 0.10% by mass or5.3% by atom or more, further preferably 0.20% by mass or more or 10.1%by atom or more.

(1-1-2-3) Amorphous Phase

In the instant specification, the “amorphous substance” or “amorphousphase” refers to a phase having no long distance order in the range, andhaving no distinguished peak derived from the crystal structure in anX-ray diffraction spectra. When the metal-based structure contains anamorphous part or a hydrogen-containing amorphous part, plasticdeformation easily occurs, thus resulting in obtaining the excellentsintering property and adherence. The metal-based structure ispreferably an amorphous single phase, in terms of the excellentsintering property or adherence. When the metal-based structure isamorphous, magnetic or mechanical isotropy is provided to themetal-based structure, whereby a material which is magnetically ormechanically excellent can be obtained.

The present inventors have found that the amorphous structure containinghydrogen and containing it in an amount equal to or more than aspecified value has an excellent shape-controlling property of themetal-based structure (magnetic field alignment property, adherence,formation of shape anisotropy, and formation of a formless phase). Whenthe metal-based structure contains hydrogen and/or the metal-basedstructure contains the amorphous part, accordingly, it is easy to formvarious shapes as the whole structure, due to the effect in which thedeformation property and the adherence of the metal-based structure,nanostructure or nanoparticles are improved. This tendency is remarkablein liquid, and is more remarkable in liquid containing ahydrogen-containing substance.

When the metal-based structure contains the amorphous part, it ispreferable to obtain an X-ray diffraction spectra showing existence of ametal phase in the state in which the metal-based structure iscrystallized by heating. In that case, the material providing the metalphase forms of the amorphous part, and thus it becomes clearer that themetal-based structure before heating contains the amorphous part. Here,the X-ray diffraction spectra of the metal-based structure, obtained byheating the metal-based structure to be crystallized, may be spectrashowing that the metal-based structure is a metal single phase. Here,the metal single phase refers to a phase formed of metals alone,containing no phase other than the metal phase such as oxides. They maybe exemplified by metal element single phases, alloy, semi-metal, andintermetallic compounds, formed of elements selected from metal elementand/or semi-metal element, and solid solutions, mixtures in which theelements described above are mixed and composites thereof.

The reason in which the metal-based structure according to oneembodiment of the present invention contains the amorphous part can beconsidered as follows: It can be said, accordingly, that the hydrogen inthe metal-based structure influences the formation of the amorphouspart, and thus when the hydrogen is contained in the metal-basedstructure the crystallization is inhibited during the development of ametal-based reduced substance; as a result, an amorphous region or aregion being close thereto is produced in the metal-based structure.

It is possible to obtain a state which can be considered to be amorphousover the whole area, observing substantially no peak in the X-raydiffraction spectra of the metal-based structure, i.e., the metal-basedstructure of the amorphous single phase, by appropriately controllingproduction conditions. As described below, in Examples of the presentinvention, the metal-based structure which is the amorphous single phaseand contains hydrogen is obtained, and, from the results, it can beunderstood that the amorphous part is the hydrogen-containing amorphous.It can be said that in such an amorphous substance, andhydrogen-containing amorphous phase, the adhesion of the metal-basedstructures to each other, or the adhesion of the nanopart structuresforming the metal-based structures to each other is made easy, becauseof the high plastic deformation property and binding property.

Specifically, a metal-based structure providing an X-ray diffractionspectra shown in FIG. 42 is a structure in which the reduced substanceis Fe and peaks derived from the crystal structure are not observed.When the metal-based structure is heated, a crystallized metal-basedstructure can be obtained in which only peaks substantially belonging toαFe with a body-centered cubic lattice structure in an X-ray diffractionspectra are obtained, as shown in FIG. 43. From the above, it can beunderstood that the metal-based structure mainly contains the amorphouspart containing the Fe single element metal as a main component in thestate before the heating.

DSC (differential scanning calorimeter) results obtained when ametal-based structure, obtained in the same manner as that of ametal-based structure having a filament wavy shape shown in FIG. 32, isheated to 500° C. (a temperature rising rate: 3° C./minute) are as shownin FIG. 56. It can be said that heat generation having a peak at around460° C. is based on the crystallization. It can also be said that achemical change or a state change providing heat generation having apeak at around 320° C. is caused by a structural change with acrystallographic and/or chemical change.

(1-1-3) Single Element Metal

The metal-based structure according to the present invention can beformed from a single element metal. It is known that an amorphous phaseof the single element metal (pure metal) can be produced by a vacuumdeposition method at a very low temperature. Bi is the first successfulcase according to the vacuum deposition method, and after that, Ga, Fe,Ni, Cr, Au, and the like have been produced. However, any of them areinstable, and they are crystallized at room temperature or lower. Forthat reason, substances, which are generally called as an amorphousmetal, are all alloys.

In particular, an amorphous phase of Fe single element which is stableat room temperature has not been confirmed in previous examples for Fe.There has been an example in which amorphous substance is formed inaround an Fe₂B composition, which has been put to practical use. Knownamorphous Fe₂B is produced by a rapid solidification processing, and aribbon-shaped amorphous form can be obtained by quick cooling the meltedFeB to room temperature.

According to the present invention, the amorphous phase of the singleelement metal can be formed. In Examples, amorphous phase of Fecontaining hydrogen could be stably obtained. From the above, it can beconsidered that the amorphous phase can be formed by containinghydrogen. The mechanism of the amorphous formation can be consideredthat, as described above, the crystallization of Fe is inhibited byforming a binding reaction state, which has not been known until now,between Fe and hydrogen, which have hitherto been considered to be acombination having a very low reactivity, whereby the amorphous phase isformed.

(1-1-4) Self-Granulating Reaction and Magnetic Substance (1-1-4-1)Self-Granulating Reaction

In the present invention, the self-granulating reaction refers thatparticle formation is advanced only by setting reaction conditions andleaving a starting material to stand, to obtain a formation of particleshaving a specific shape, structure (amorphous structure), composition,and hydrogen content. For example, in a case of a reducing depositionreaction by a two-liquid mixing method, described below, the granulationmay be advanced by minimizing application of a mechanical external forceto deposited particles by a stirring operation, and the like (control isperformed without inhibiting the self-granulating reaction) (seeExamples).

A driving force forming and maintaining the specific amorphous structurecan be assume to be a magnetic property of the whole particle. Probably,it is considered that an influence of a size for forming a singlemagnetic domain structure is large. At an initial stage of deposition,an amorphous substance of a magnetically specific structure is formed,particles grow by a surface energy driving force to increase a particlesize, and the particle growth is inhibited at the time at which theparticle size reaches a magnetically stable particle size, for example,a particle size having the minimum magnetic energy based on the singlemagnetic domain structure. It is considered that amorphous particleshaving a uniform specific particle size can be formed by this mechanism.The mechanism in which the specific amorphous structure can beselectively formed at the initial stage of deposition may be a mechanismof natural selection. It is considered that only the particles havingthe specific amorphous structure grow; whereas, particles having nospecific structure relatively turn to an unstable state as they grow,and they stop growing or disappear.

The size and the amorphous structure of the particle are determinant ofmagnetism of the particles, and thus a determinant of a state of aparticle is energy based on the magnetism and the surface energy of theparticle, and amorphous structure and size (for example, a particle sizewhen it is assumed as a sphere). Summarizing the above, in a case ofExample, there are two kinds of stable amorphous magnetism particlestates (an amorphous structure and a size), which are separated by ametal-based ion concentration. It is assumed that the self-granulatingreaction whose driving force is the change to the stable state occurs.

(1-1-4-2) Magnetic Field Alignment

When the shaped particles formed by the self-granulating reaction areaggregated and aligned in a magnetic field, a secondary structure can bevery effectively formed because of the uniform property. At that time,the secondary structure can be very effectively formed by the effect ofimproving the adherence, when the H % is the specified value or more,and the amorphous phase is contained.

(1-1-4-3) Magnetic Substance

From the above, the metal-based structure according to the presentinvention may be formed of the magnetic substance. In the instantspecification, the “magnetic substance” refers to a substance which ismagnetized in a magnetic field. The material forming the magneticsubstance may include metals, semi-metals, intermetallic compounds,metal compounds, borides, phosphides, sulfides, oxides, and the like. Inparticular, the metals, the intermetallic compounds and the metalcompound are preferable, and substances containing a transition (metal)element are also preferable. Further, substances containing aferromagnet element (Fe, Ni, Co, Gd, or the like) are preferable. Whenthe nanoparticles are handled, there is a case in which a bulk body,which is a large lump, and the magnetic property are different from eachother.

(1-1-5) Nucleating Agent

The metal-based structure may be a structure obtained by reduction inliquid, as described below. In the instant specification, the “liquid”may be a solution or a dispersion. The liquid is preferably thesolution, in terms of the improvement of the controlling property of theform of the metal-based structure. It is preferable, accordingly that atleast a part of the reducible substance is dissolved in liquid. Theliquid may be liquid containing a no nucleating agent which can be morepreferentially reduced than the reducible substance.

Here, in general, the nucleating agent is added in order to act as anuclear for forming a fine particles or fine structures from thereducible substance by an action of promoting the deposition of thereducible substance, for example, formation of fine particles by morepreferential reduction than that of the reducible substance, and thelike.

According to conventional techniques, it is generally performed in termsof stable advance of formation of nanoparticles that a substance whichcan form a reduced substance (such as a metal) including the reduciblesubstance is put in liquid, a reducing agent and a nucleating agentcontaining a substance from which a crystal nucleus (e.g. platinumparticles) is formed are added to the liquid, a reduced substance isdeposited from the reducible substance, a component based on thenucleating agent being as a nucleus, and the deposited product is grownto form nanoparticles. When such a nucleating agent is contained,however, the component based on the nucleating agent is necessarilycontained in the nanoparticle; as a result, a metal-based structureformed from the nanoparticle has a decreased degree of freedom in thecomposition. In addition, the magnetic characteristics and themechanical properties of the metal-based structure may be restricted bythe component above. When the liquid does not contain the nucleatingagent in the reduction of the reducible substance, the degree of freedomin the composition of the metal-based structure can be increased, or theranges of the magnetic characteristics and the mechanical properties canbe widened. Furthermore, the accuracy of the shape control can beincreased by the effects and high purity metal-based structure.

The liquid described above does not need to use a nucleating agenthaving an ionization tendency smaller than that of the reduciblesubstance. The liquid does not need to use a nucleating agent containinga metal or semi-metal element other than the reducible substance. Theliquid does not need to use the nucleating agent.

From the above, the metal-based structure according to the presentinvention does not need to contain the nucleating agent.

(1-1-6) Metal-Based Structure Formed from Hydrogen Compound, Cluster orAggregate Thereof Represented by General Formula: M_(m)H

(1-1-6-1) Hydrogen Compound, Cluster or Aggregate Thereof Represented byGeneral Formula: M_(m)H (Mix Proportion of Hydrogen Content (m Number))

From measurement results in Examples, it is confirmed that the hydrogencontent in the metal-based structure of the present invention is a mixproportion according to a specific rule, “specific mix proportion.” Inthe metal-based structure, in order to have the “specific mixproportion,” aggregates which are smaller than the structure are formedin the same mix proportion, then the structure and the mix proportionare stably formed; in other word, when the aggregates or clusters of thedeposited particles, or nanoparticles of aggregation thereof have thespecific mix proportion, the structure is stably formed. The reason inwhich the specific mix proportion is attained can be understood byformation of deposited aggregates or “H clusters” with a “shellstructure” and a “regular polyhedron structure.” In particular, thestructure containing a metal element or being a metal single element(Fe) conforms to a regular polyhedron rule. From this, the presence ofaggregates or clusters having a regular polyhedron structure or astructure which has the same mix proportion (atomic ratio) as that ofthe regular polyhedron structure is specified.

The “H cluster” formed of a metal-based atom and hydrogen, which is acluster in the present application, is an aggregate of a metal-basedatom and hydrogen, having a mix proportion of m:1 wherein m is aninteger of m≥3. The H clusters are aggregated to form a nanoparticle anda metal-based structure, and further a nanostructure formed article suchas a nanowire. When 3≤m (the upper limit is preferably m≤300), it isformed in a range of the hydrogen content of (the lower limit ispreferably 0.33 at % from the upper limit of the m number, 300) to 25 at% (corresponding to 3≤m).

It is considered that because there is a limit in the kinds of thebonding state between H and the metal-based atom, there are intervals inthe m number. The numbers at intervals are called “magic numbers” and itis known as a phenomenon in which the specific number of structuresstably exist in an atomic nucleus structure or a metal clusterstructure. For example, it is known that Na metal clusters stably existat the number of atoms of 8, 20, 40, 58, 92, 138, 198, 264, 344, 442,554, and larger numbers at intervals.

In the H cluster, the m number changes depending on the mix proportionof the metal-based atom to hydrogen. In particular, it has been foundthat a case where the metal-based atom is a metal element, or is a metalsingle element (Fe) conforms to a regular polyhedron rule. From thatresult, a “regular polyhedron structure” in which hydrogen is disposedat the center and metal-based atoms are disposed around it like a shellis formed, which conforms to the “regular polyhedron H clusterstructure” in which the distance to the hydrogen is equal and thedistances between the adjacent metal-based atoms are equal. Further, asin Examples, regular polyhedron H clusters containing a single elementmetal, or containing Fe element are stably obtained. The “regularpolyhedron H cluster structure” includes a cluster structure formed ofstructures having the same mix proportion; in other words, also includesa distorted structure (mostly regular polyhedron structure). It ispossible to selectively form or control the m number by a kind of theatom or reaction conditions.

When the metal-based element is a transition metal, the H cluster can bestably formed by the metal bond thereof. In particular, when aferromagnetism element, Fe, Ni or Co is contained, there are cases inwhich shaped nanoparticles are easily formed by the self-granulatingreaction.

(1-1-6-2) Specific Mix Proportion “Integer Rule”:

It is a mix proportion formed by a “shell structure” in which onehydrogen atom is disposed at the center and the specific number of atomsare disposed in two-dimensionally or three-dimensionally around it. Theinteger rule, which is the mix proportion, is that M:H=m:1, wherein m≥3,and m is an integer, and H %: ˜25.0 at % (when m=3). M is formed of ametal-based atom and, as in Examples, M includes cases to be formed of ametal single element (Fe) atom or multiple metal elements, or formed ofmultiple elements of a metal(s) and a semi-metal(s). m is the number ofmetal-based atoms to one H atom, or corresponds to the total number inmultiple elements. In a case of Example 1-12-1, the metal-based elementsare Fe and B, and Fe:B=2:1, and thus the m number is m=120 to Fe and B,m=40 to an Fe₂B intermetallic compound composition, and m=80 to an Fesingle element.

“Regular Polyhedron Rule”:

It is a mix proportion formed by a “regular polyhedron structure” whichis formed by a disposition in which distances from the center can makeequal to each other, distances between adjacent atoms can make equal toeach other, and atoms are disposed at the vertex of the regularpolyhedron, the middle of the surface, and the middle of the side (theatoms are not disposed at mixed positions, for example, the vertex andthe middle). The number of atoms disposed on the “regular polyhedronstructure” is the number selected from 4, 6, 8, 12, 20, and 30. In the“regular polyhedron rule,” M:H=m:1, and m takes a value selected from 4,6, 8, 12, 20, and 30. H %: 3.2 to 20.0 at %. This structure is easilyformed when M is a metal element, and is a single element metal.

(1-1-6-3) Mix Proportion of Hydrogen Content and Transition MetalElement

It is preferable that the metal-based structure is formed of themetal-based structure, nanoparticles or clusters having a specifiedvalue or more of H %, more preferably containing a metal element. Inorder to perform further stably the production, it is preferable thatthe metal-based element contains the following element, more preferablethat it is selected from the following element group.

(1) “Metal elements excluding” alkali metals (Li, Na, K, Rb, Cs, and Fr)and alkaline earth metals (Ca, Sr, Ba, and Ra) are preferable as anelement having a higher metal binding property.(2) Further, “transition metal elements” having a higher metal bindingproperty are desirable. The transition metal elements are elementsbelonging to the range of group 3 to group 12 in the periodic table.There are cases in which elements belonging to the range of group 3 togroup 13 in the periodical table are preferable. In addition, there arecases in which transition metal elements belonging to the range of group3 to group 11 in the periodical table are more preferable.(3) Among (2) above, there are cases in which the element selected fromSc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu is particularly preferable.(4) There are further cases in which the element selected from Fe, Coand Ni, which show ferromagnetism, is particularly preferable in theformation of particles according to the self-granulating reaction.(5) Further, as shown in Examples, Fe is preferable in the stableproduction. In general, Fe tends to be easily oxidized in a solution,and it is difficult to form it according to conventional methods, andthus the production method of the present application is particularlypreferable in terms of the stability of the production and thereliability of properties.

(1-2) Shape Characteristic

Here, shape characteristics in the metal-based structure according toone embodiment of the present invention are explained. The shapecharacteristics in the present invention are as described below, and itis specific that the structure has the following shape though it is theamorphous phase.

The metal-based structure according to one embodiment of the presentinvention may contain granular materials having a size of at least morethan 1 nm as a part structure or the whole structure. In the instantspecification, the phrase “a part structure of the metal-based structurehas a size of at least more than a certain length (1 nm in the abovecase)” refers that the whole of the part structure of the metal-basedstructure cannot be put inside of a sphere whose diameter is the same asthe length. Specifically, it means that the part structure always has apart which cannot be put in the circle having a diameter of the certainlength in an observation with a secondary electron microscope. When themetal-based structure according to one embodiment of the presentinvention contains the granular materials as the whole structure, themetal-based structure is formed of the granular materials. Specificexamples in such a case may include a metal-based structure containinggranular materials with a bead shape described below as the wholestructure.

The metal-based structure according to one embodiment of the presentinvention may contain a nanopart structure, which is a part structurehaving a part whose size is at most less than 1 μm, detectable with asecondary electron image in the observation with an electronicmicroscope, and at the same time may have a size of at least more than10 μm as a whole. In the instant specification, the “part structurehaving a part whose size is at most less than 1 μm” means a structure inwhich when a virtual sphere having a diameter of 1 μm is overlapped onthe metal-based structure, the characteristics of the part structure canbe found inside the sphere.

The metal-based structure containing the nanopart structure according toone embodiment of the present invention specifically may have thefollowing shapes. It can be assumed that the amorphous phase containinghydrogen according to the present invention can have the followingshapes owing to the self-granulating reaction, though it is theamorphous phase.

(1-2-1) Wire (Filament and Filament Yarn)

The metal-based structure containing the nanopart structure according toone embodiment of the present invention may have a wire shape (filamentor filament yarn shape). Here, a terms “filament” corresponds to a term“long fiber” in the fiber field, and the “filament yarn” means a threadobtained by spinning the long fibers.

In the instant specification, when a metal-based structure observed hasa thread shape, has an aspect ratio, a ratio of the longest axial lengthto the shortest axial length, of 5 or more, and is formed of nanopartstructures having one thread shape, then the metal-based structure isreferred to as a filament. As the filament has the nanopart structure,the shortest axial length is less than 1 μm.

On the other hand, when the metal-based structure observed has an aspectratio of 5 or more, and is formed of nanopart structures having multiplethread shapes, then the metal-based structure is referred to as afilament yarn.

FIGS. 8 and 9 show examples of observation images of metal-basedstructures with filament shape and filament yarn shape, respectively.The metal-based structures are observed which have a thread shape with alength of 10 μm or longer and a short axial length of less than 1 μm,and have a filament yarn shape of an aspect ratio of 5 or more. Any ofthe filament and the filament yarn is the metal-based structure havingthe part structure with the shape anisotropy, because the aspect ratiois 5 or more.

In the present invention, the anisotropy means that physical propertiesof a substance differ depending on the direction, and the shapeanisotropy means a shape biased in any direction.

The wire structure has preferably an average short axial length of 50 to250 nm.

(1-2-2) Filament Web

The metal-based structure according to one embodiment of the presentinvention may have a web shape, formed from the metal-based structureshaving the filament yarn shape. In the instant specification, themetal-based structure having the web shape is referred to as the“filament web.” Here, the “web” is as defined in the fiber field, andmeans a fiber aggregate and a three-dimensional member obtained byinterlacing or binding fibers at multiple points. The nanopart structureforming the metal-based structure with the filament web shape is thefilament, and accordingly, the filament web is a metal-based structurehaving a part structure with the shape anisotropy.

FIG. 12 shows one example of observation images of the metal-basedstructure having such a filament web shape. It can be understood fromFIG. 12 that the three-dimensional member is formed by binding orinterlacing the multiple filaments. There are cavities in the filamentweb because the multiple filaments, forming the web, are disposedseparating from each other. Such a filament web, accordingly, has ashape capable of functioning as a three-dimensional mesh. In this case,the metal-based structure according to one embodiment of the presentinvention contains a part structure having a mesh shape (FIGS. 13 to15).

(1-2-3) Staple and Staple Web

It cannot be said that the metal-based structure according to oneembodiment of the present invention is formed of the metal-basedstructure having a particularly high aspect ratio, as the filament web,but it may have a web shape having a three-dimensional mesh-shapedstructure. FIG. 3 shows one example of observation images of themetal-based structures having such a shape.

As shown in FIG. 3, the metal-based structure having the web shape has ashape close to a shape obtained by interlacing multiple short fibers(staples), and thus in the instant specification, the web shape isreferred to as the “staple web.” The nanopart structure forming themetal-based structure having the staple web shape is a staple. Thestaple is the nanopart structure, and thus the shortest axial length isless than 1 μm. The staple web, accordingly, is a metal-based structurehaving a part structure (staple) having the anisotropy.

(1-2-4) Bead (Spherical Shape) and Bead Wire

The metal-based structure according to one embodiment of the presentinvention may have a bead wire shape formed of multiple bead (spherical)nanopart structures. In the instant specification, the “bead” means ananopart structure having a shape with an aspect ratio of less than 2.In the instant specification, accordingly, the “staple” has ananisotropy which is higher than that of the “bead” and less than that ofthe “filament.” In addition, in the instant specification, the “beadwire” refers to a metal-based structure obtained by connecting multiplenanopart structure having a bead shape while they are aligned, having anaspect ratio of 5 or more. The bead wire is, accordingly, a metal-basedstructure having a part structure having anisotropy.

FIG. 36 shows one example of observation images of metal-basedstructures having such a bead wire shape. Many metal-based structureshaving bead wire shape having a length of 10 μm or longer are observed.

FIG. 37 is an observation image showing one part enlarged of FIG. 36,and it can be understood from FIG. 37 that the nanopart structure isformed of multiple beads, specifically, a linear object is formed byaligning multiple beads having an aspect ratio of about 1, which can beexpressed as a sphere. Specifically, one bead is connected to one beadin a long axis direction. It can be considered that beads form a line inone direction one by one, and they are stuck to each other. According toFIGS. 36 and 37, the aspect ratio of the bead wire is far more than 5.

The bead (spherical) particle structure has preferably an average lengthof 150 to 500 nm.

(1-2-5) Bead Web

The metal-based structure according to one embodiment of the presentinvention may have a three-dimensional shape obtained by binding orinterlacing the multiple bead wires. In the instant specification, sucha shape is referred to as a “bead web.” The metal-based structure havingthe bead web shape is formed of nanopart structures having the bead wireshape. The bead web, accordingly, is a metal-based structure having apart structure (bead wire) having the anisotropy. FIGS. 36 to 38 are oneexample of observation images of the metal-based structures having sucha bead web shape. FIG. 36 is the image in which a part of FIG. 38 isenlarged. In the metal-based structure having the bead web shape shownin FIG. 36, multiple metal-based structures having the bead wire shape,which form the above, are bounded while they are oriented.

On the other hand, a metal-based structure according to FIG. 16, whichis another example of the observation image of the metal-based structurehaving such a bead web shape, has a shorter length of each bead wireforming the bead web compared to the metal-based structure shown in FIG.36, and consequently a degree of interlacing of the bead wire is large.

As shown in FIG. 16 and FIG. 38, the metal-based structure having thebead web shape has a shape capable of functioning as a three-dimensionalmesh. In that case, accordingly, the metal-based structure according toone embodiment of the present invention contains a part structure havinga mesh shape.

(1-2-6) Bead Bulk

The metal-based structure according to one embodiment of the presentinvention may have a shape in which multiple nanopart structures havinga bead shape have a particularly low degree of connection while thebeads are aligned, and the multiple nanopart structures are almostisotropically bound to each other. In the instant specification, amassive shape formed of multiple nanopart structures having such a beadshape may sometimes be referred to as a “bead bulk.” FIG. 20 is also oneexample of observation images of the metal-based structures having thebead bulk shape.

(1-2-6) Average Length of Particle Structure or Average Size (ParticleSize) of Particle Structure when Particle has Spherical Shape

An average length of particle structures or an average size (particlesize) of the particle structures when the particles have a sphericalshape can be obtained from an average value of short axis lengths d offilaments, staples, bead wire, or bead bulks. When the metal-basedstructure is based on the shape of staples or filaments, particleshaving uniform sizes between 110 and 150 nm (referred to as “100 F”) areobserved. It is preferable that 100 F has a particle size of 50 to 250nm, more preferably 50 to less than 175 nm, still more preferably 100 toless than 175 nm. When the metal-based structure is based on the beadshape, particles having uniform size from 200 to 330 nm (referred to as“300B”) are observed. It is preferable that 300B has a particle size of150 to 500 nm, more preferably 175 to 400 nm or less, still morepreferably 175 to 350 nm or less.

(1-3) Formless Phase

The formless phase according to the present invention is explained.

(1-3-1) Characteristic of Formless Phase

The formless phase is an amorphous phase, has (a) a high adherence and(b) a high filling ability, and forms a filled phase. The state having ahigh hydrogen content has particularly high effects.

FIG. 20 shows a phase formed of particles having a size of about 300 nm,which are seen white, and a formless phase. In FIG. 20, white thinbeard-like parts are observed. These are billowing edges of fracturesurfaces, observed when, for example, two glass plates are stuck to eachother through grease and then the plates are peeled off from each other,which are observed as white beard-like substances. Protruded parts areobserved white because of a characteristic of SEM. This is acharacteristic fracture surface of the formless phase. These parts havea morphological character similar to starch syrup, they exist so thatcavities of 300 nm particles are filled up, and a minute structure withno cavities is formed as a whole. In addition, a state in whichductility is high is observed as shown in FIG. 21. In FIG. 21, thestructure formed of the formless phases alone is observed. Form this, itis understood as shown in FIGS. 20 and 21 that the formless phase is theamorphous phase, the adherence between the formless phases is high dueto the particularly high H content, and the filling ability capable offilling the cavity is high, whereby a minute solidified substance withsubstantially no cavities is formed. Even after the crystallization by aheat-treatment, as shown in FIG. 25, aggregates of nanoparticles, whichare minute solidified substance with substantially no cavities (sinteredbodies), are obtained. This happens because the effect in whichsolidified substances with substantially no cavities are formed in thesolidified substance before the heat-treatment, as shown in FIGS. 20 and21, is large. From this, it is understood that the formless phase has ahigh effect of refinement of the sintered bodies.

(1-3-2) Specific Example of Formless Phase According to One Embodimentof Present Invention

Here, the formless phase is explained using a case in which themetal-based structure according to one embodiment of the presentinvention has a bead-shaped nanopart structure as a specific example.

FIGS. 22, 20 and 23 are images showing a degree of formless phasegeneration, when metal-based structures taken out from liquid, having abead bulk shape, are subjected to heat-treatment in heat-treatmentcondition 1 (details are described below) following drying condition 1(details are described below).

FIG. 22 is an image when metal-based structures are observed which aresubjected to a heat-treatment in the heat-treatment condition 1 in whichthey are held at 50° C. for 2 minutes, and then are cooled to roomtemperature. Each shape of the bead-shaped nanopart structures formingthe bead bulk is easily confirmed, and it can also be confirmed thatthere are many cavities between the beads.

On the contrary, when metal-based structures are observed which aresubjected to a heat-treatment in the heat condition 1 in which they areheld at 200° C. for 2 minutes, and then are cooled to room temperature,as shown in FIG. 20, formless phases, which are observed transparentlyto semi-transparently, are generated so that they surround the wholebead-shaped nanopart structures forming the bead bulk in an observationimage according to a secondary electron microscope; as a result,cavities of the metal-based structure are filled with the formlessphase, and a minute solidified substance having substantially no or verysmall amount of cavities are formed.

When metal-based structures are observed which are subjected to aheat-treatment in the heat-treatment condition 1 in which they are heldat 300° C. for 2 minutes, and then are cooled to room temperature, asshown in FIG. 23, the number of the formless phases is decreasedcompared to the case in which the heating temperature is 200° C., and apart of cavities in the metal-based structure are filled with theformless phase.

The metal-based structure according to one embodiment of the presentinvention, as shown in FIG. 23, may further have a formless phase whichexists so that at least a part of a cavity defined by multiplebead-shaped nanopart structures, is filled.

The metal-based structure according to one embodiment of the presentinvention, as shown in FIG. 20, may have a formless phase which existsso that the multiple bead-shaped nanopart structures are dispersedtherein.

The metal-based structure according to one embodiment of the presentinvention may contain both of the two modes of the formless phase. Asshown in FIG. 20, the structure may have a structure in whichbead-shaped nanopart structures are dispersed in a formless phase and,at the same time, the multiple bead-shaped nanopart structures areconnected to each other, and a formless phase exists so that a cavitydefined by the bead-shaped nanopart structures is filled. Furthermore,as shown in FIG. 21, the formless phase may exist so that it is asubstantial single phase.

The formless phase is not observed only in the metal-based structureshaving the bead-shaped nanopart structures or is not first observed whenthe metal-based structure is heated. For example, as shown in FIG. 5,the formless phase can be observed in the metal-based structure havingthe staple web shape. The metal-based structure having the staple webshape according to FIG. 5 is obtained by observing the structure whichis taken out from liquid, and then dried at room temperature without anyspecific heating treatment. There are cases, accordingly, in which theformless phase can be observed even if the heating treatment is notperformed.

The composition of the formless phase is not necessarily clear. However,when the hydrogen content in the metal-based structure is high, it isobserved that there are many formless phases. In such a case, it can beconsidered that hydrogen is contained in the formless phase. It isfurther considered that the hydrogen inhibits the oxidation of the metalsubstance contained in the metal-based structure.

As described above, the metal-based structure according to oneembodiment of the present invention may contain the amorphous part. Whenan X-ray diffraction measurement is performed for metal-based structures(FIG. 9) formed of multiple metal-based structures having a filamentyarn shape shown in FIG. 8 and having a filament web shape, resultsshowing to be a structure having a high non-crystallinity are obtained,as shown in FIG. 40.

A threshold value of the formless phase can be summarized as follows:

(1) When the hydrogen content in the metal-based structure is adjustedto 0.41% by atom (0.01% by mass) or more, the formless phase is formed.(2) When the hydrogen content in the metal-based structure is adjustedto 2.7% by atom (0.05% by mass) or more, preferably 5.3% by atom (0.10%by mass) or more, more preferably 10.1% by atom (0.20% by mass) or more,the formless phase is easily formed.(3) When the content of the reducible substance is adjusted to 0.3mmol/kg or more, provided that the saturated concentration is the upperlimit, the formless phase is formed. When the content is adjusted to thelower limit of 0.3 mmol/kg to less than 150 mmol/kg, preferably lessthan 60 mmol/kg, more preferably less than 15 mmol/kg, the formlessphase is easily formed. When the lower limit is adjusted to 1 mmol/kg,the formless phase is more stably formed.(4) When a solvent contains an alcohol, the formless phase is easilyformed.

In particular, when the metal-based structure contains a ferromagneticsubstance, particularly Fe, the formless phase is easily formed when theconditions (3) and (4) above are satisfied.

(1-4) Cluster Structure and Nanoparticle, which is Aggregate of ClusterStructure

(1-4-1) Cluster Structure

A measurement result of a hydrogen content of a structure formed of anamorphous single phase and containing a wire shape/formless phase,obtained in the present study, is that Fe:H=20:1.12 or 8:0.98. From themix proportion, a cluster structure of a regular dodecahedron of Fe₂₀Hin which Fe atoms are disposed on 20 vertexes and an H atom is disposedat the center or a regular hexahedron (cubic) of Fe₈H having the samecomposition can be approximately considered as the minimum unit.

The cluster structure is the minimum structural unit as a compoundmolecule, the composition and the structure thereof are decided, and thecrystal thereof is not grown. When it is considered that the amorphousnanoparticles are formed by forming aggregates of the cluster, theconsistency with the experimental result can be obtained. It can bereasonably understood, accordingly, that the amorphous nanoparticleshaving the uniform composition, structure and physical properties areformed by aggregation of the cluster-type compound.

It is considered that a stable shape and size are formed by agranulation reaction by self-control (self-granulating reaction), whichoccurs during the aggregation of the clusters due to a magnetic natureof the nanoparticle and a surface effect, whereby uniform shape and sizeof the amorphous nanoparticles can be obtained.

(1-4-2) Amorphous Particle by Usual Reduction Deposition (Containing NoHydrogen)

The amorphous particle is basically formless. An amorphous substancecontaining no hydrogen is easily oxidized, and thus it forms intoparticles by tearing off it with stirring and oxidizing surfaces of theteared pieces, or in a mechanism in which the substance originallycannot aggregate more than a certain size—the oxidation is advanced inthe course of the aggregation, and thus they cannot stick to each other(i.e., oxidation); in other words, in the case of the usual amorphoussubstance containing no hydrogen, it is not that the particles areformed, but formless phase, which is a large aggregate, cannot be notformed because oxidation occurs. When stirring is performed, which issimilar to mechanical pulverization, the uniform size of the pulverizedparticles can be obtained by making pulverization conditions constant.

In the present application, it is difficult to cause the oxidationbecause hydrogen is contained, and thus the formless phase (aggregatehaving a size of several hundred nm or more) is formed by aggregation ofthe formless phase component, or insertion into between particles.

(1-4-3) Aggregate of Cluster Structure and Particle Shape

In Examples, both regular dodecahedron clusters and regular hexahedronclusters are clusters having short distance order, and have a nature inwhich the aggregate becomes amorphous (do not form long distance order).This is led by an experimental fact in which an amorphous substance iswholly formed by containing hydrogen in a high content while controllinga metal composition with a single element.

It is specific that shaped nanoparticles are formed as in the presentapplication. In the regular dodecahedron, the clusters thereof formnanoparticles having a size of about 100 nm (hereinafter referred to as“100 F”) and the growth is self-completed. It can be considered,accordingly, that the shape and size of the aggregate areself-controlled by the magnetism thereof—the growth is stopped when amagnetically stable shape is attained, whereby uniform 100 F particlesare formed. The wire structure is a structure in which the 100 Fparticles are aligned in a magnetic field (FIG. 31).

In the case of the regular hexahedron, the clusters thereof formnanoparticle having a size of about 300 nm (hereinafter referred to as“300B”) and then the growth is self-completed. The same mechanism as in100 F acts, but it can be considered that the magnetism thereof is weak,and thus large particles are formed. The particles are aligned in amagnetic field, as similar to above, and a bead wire is formed (FIG.27).

(1-4-4) Formation of Formless Phase

The formless phase is formed by collapsing 300B (collapse factor), orthe formless phase is formed without formation of 300B (aggregationinhibition factor); in short, it can be considered that the formlessphase and 300B are formed of the same substance (regular hexahedronclusters), which are transitively changed amorphous nanoparticle shapes(shaped/formless) in transitive conditions in Examples.

In FIG. 20, a phase in which 300B and the formless phases are mixed isformed. In FIG. 21, almost all part of the phase is formless. FIG. 27shows a bead wire obtained by applying a magnetic field to beads,whereby they are aligned and stuck to each other, and in FIG. 27, aformless phase cannot be observed and almost all part is formed of onlybeads (300B). The shape formed of beads only turns to an amorphoussingle phase (FIG. 44) after drying, and turns to an αFe single phase,from XRD results (Example 1-9-3) after a heat-treatment, and samestructure change occurs and the same composition is obtained as in thecase of FIG. 20 in which the formless phase is contained. Form those, itcan be understood that both of 300B and the formless phase are amorphousand have the same composition (Fe single phase). It can be consideredthat the reason in which only beads are formed by applying the magneticfield is that the particles are selectively aggregated by the magneticfield, and the beads are bound to each other in a bead wire shape. Thereis a possibility in which it is difficult to gather the formless phasesbecause the phase has a slightly weak magnetic field or is easilyinfluenced by a resistance of a solvent; as a result, the phases arecasted away during a washing step. It is also considered that the beadshape becomes stable by the effect of the magnetic field, i.e., it isdifficult to collapse the shape by the effect of the magnetic field. Incomparisons of FIGS. 20, 22 and 23, the amount of the formless phases ischanged by a drying temperature (a heat-treatment temperature).

In FIG. 5, a formless phase is formed from staples in a condition inwhich ethanol is added to a solvent. It is considered that the additionof ethanol to the solvent hinders aggregation of clusters, or inhibitsformation of shaped particles, thus resulting in formation of theformless phase (aggregation inhibition factor), or the cluster structureis changed by addition of ethanol to the solvent, thus resulting inincrease of the hydrogen content.

2. Structure Based on Metal-Based Structure (2-1) CrystallizedMetal-Based Structure

A crystallized metal-based structure in which at least a part thereof isformed of crystal phases, according to one embodiment of the presentinvention, is obtained by crystallizing the metal-based structure byheating, or the like. Conditions for crystallization (when thecrystallization is performed by heating, the conditions may concretelyinclude a temperature, an atmosphere thereof, and the like) areappropriately decided based on the structure or composition of themetal-based structure. For example, a metal-based structure shown inFIG. 32, having a filament web shape and using Fe as a metal-basedreduced substance, has a heat generation peak at 500° C. or lower, whichcan be considered to be based on the crystallization, as shown in FIG.56.

When the metal-based structure according to one embodiment of thepresent invention is heated to a temperature higher than acrystallization temperature, a crystallized metal-based structure maysometimes be obtained which has a structure with a decreased volume ofcavities defined by nanopart structures, or a structure in whichcavities substantially disappear.

FIG. 24 and FIG. 25 are examples of observation images of beadbulk-shaped metal-based structures heated to 400° C., and FIG. 43 is oneexample of X-ray diffraction spectra of a metal-based structure obtainedby heating to 600° C. The bead bulk-shaped metal-based structure is astructure having a formless phase after a heat-treatment at 200° C., asshown in FIGS. 18 to 21. FIG. 25 is an enlarged view of a part of FIG.24, and it is seen that a minute solidified substance formed ofnanoparticles having substantially no or a slightly small amount ofcavities is formed by crystallization or sintering, which is advanced byheating to 400° C. From the results of FIG. 43, it is observed that astructure formed of high purity metal phase (αFe) is formed.

FIG. 35 shows one example of observation images of bead bulk-shapedmetal-based structures heated to 600° C., and FIG. 50 is one example ofX-ray diffraction spectra of a metal-based structure obtained by heatingto 600° C. FIG. 33 and FIG. 34 are examples of observation images ofbead bulk-shaped metal-based structures heated from 150° C. to 200° C.,and it is observed that the bead-shaped nanopart structures are almostisotropically connected to each other, and it is a metal-based structurecontaining formless phases in a very small amount. As shown in FIG. 35,a state in which the crystallization or sintering is advanced by heatingto 600° C., thereby decreasing cavities is observed, but a structureformed of nanoparticles has many cavities. It is also observed from theresults of FIG. 50 that an intermetallic compound single phase of Fe₂Bis formed.

From the results as described above, when the formless phase existsand/or the metal-based structure contains hydrogen, the hydrogen contentis 0.4% by atom (0.01% by mass) or more, or 2.7% by atom (0.05% by mass)or more, and/or the metal-based structure contains the amorphous part,it is easy to form the solidified substance formed of the nanoparticles,and further it is easy to form the minute solidified substance formed ofthe nanoparticles of the high purity metal-based structure.

FIG. 27 is one example of observation images of metal-based structureshaving a bead web shape, which have been heated to 250° C., and FIG. 28shows an observation image of a metal-based structure, obtained byheating the metal-based structure shown in FIG. 27 to 600° C. It isunderstood that the diameter of the nanopart structure having the beadshape is increased by advance of crystallization or sintering, therebydecreasing a volume of a cavity defined by the nanopart structures.

When the metal-based structure shown in FIG. 27 is further heated to800° C., the diameter of the nanopart structures having a bead shape islarger, as shown in FIG. 29, and a minute solidified substance formed ofnanoparticles of a metal-based structure having substantially nocavities is formed. From the measurement results of XRD after aheat-treatment at 600° C. (FIG. 63), it is understood that the minutesolidified substance is a nanostructure formed of αFe single phase or ananoparticle sintered body.

A crystallized metal-based structure obtained from the metal-basedstructure according to one embodiment of the present invention maysometimes have X-ray diffraction spectra which can be understood thatthey are obtained from a structure formed of a metal single phase. Forexample, in a case in which a metal-based reduced substance, which isobtained by reduction of a reducible substance, is Fe, X-ray diffractionspectra having a peak of an αFe single phase is obtained from acrystallized metal-based structure, obtained by heating a metal-basedstructure actually formed of an amorphous substance (FIG. 65). Thereason in which the single phase material as above is obtained can beconsidered that the metal-based structure according to one embodiment ofthe present invention contains hydrogen, and when the metal-basedstructure is heated to be crystallized, the hydrogen inhibits oxidationof the metal-based reduced substance contained in the metal-basedstructure.

(2-2) Composite Structure

A composite structure according to one embodiment of the presentinvention contains the metal-based structure as a part thereof. Thecontent ratio of the metal-based structure in the composite structure isnot particularly limited.

In the composite structure, the metal-based structure may be mainlycontained. Specific examples thereof may include a structure in whichanother material exists in a cavity defined by nanopart structures inthe metal-based structure (in the instant specification, which may bereferred to as an “additional substance”) or a metal-based structurewhich has been plated. In the former example, the additional substancemay be stuck to the metal-based structure. As a specific way to stickmay include heating, and pressurization. The specific composition andstructure of the additional substance are not particularly limited, solong as at least one of the composition and the structure is differentfrom those of the metal-based structure. For example, when the reducedsubstance in the metal-based structure is Fe, the additional substanceis exemplified by substances formed of a catalyst such as platinum, atungsten powder, or a ceramic powder.

The content ratio of the metal-based structure in the compositestructure may be smaller than the content ratio of the additionalsubstance. Specific examples of such a case may include sinteringmaterials using the metal-based structure as a sintering aid, resinmaterials in which the metal-based structure is dispersed.

The composite structure may contain the crystallized metal-basedstructure as a part thereof. Such a composite structure may be obtainedby containing the additional substance in the crystallized metal-basedstructure, or crystallizing metal-based structure of the compositestructure containing the metal-based structure as a part thereof. Inaddition, it may be obtained by sticking the metal-based structures toeach other. It is possible to stick part structures in the metal-basedstructure, in which the volume of the cavity in the metal-basedstructure is decreased, to each other by heating and/or pressurization.

3. Production Method of Metal-Based Structure (Introduction)

As described above, in the present application, the adherence and theformability is stably imparted to the metal-based structure by providingthe metal-based structure containing the hydrogen in a content of aspecified value or more, and in particular, in particles with nanosize,the great effects can be imparted to the stability of physicalproperties and the safety. Further, the effects are particularly largeon shape-control of a secondary structure formed of aggregates ofnanoparticles. It has been found that the formability is furtherimproved by, in addition to the inclusion of hydrogen, containing anamorphous phase, an amorphous phase containing hydrogen, or an amorphousphase formed by containing hydrogen.

Hitherto, it has been impossible or very difficult to contain hydrogenin a metal-based structure, or to contain hydrogen in concentration morethan a usual concentration range, i.e., to contain hydrogen in aconcentration more than a saturated concentration of hydrogen solidsolution in a specific state (a temperature, a pressure), or to form anamorphous substance by containing hydrogen. The reason is that it isimpossible to control a high hydrogen content, as in the presentapplication, by a usual method. By using the usual method, as a possiblemethod, in which a saturated concentration is increased by elevating apressure or temperature of hydrogen gas in an atmosphere where amaterial is put to increase the hydrogen content, or in which aconcentration of, for example, a reducing agent containing hydrogen isincreased, thereby increasing the hydrogen content in a solution in areduction reaction, it is possibly supposed that a hydrogen content in astructure is increased. According to these methods, however, it isimpossible or very difficult to increase the hydrogen content. Thus, thecontrolling the hydrogen content and the producing the substancecontaining hydrogen, as described in the present application, could nothave been achieved, except for the present invention.

In the present application, in view of the circumstance in which it isimpossible to directly control or it is possible to control the hydrogencontent only a little, a control method which has hitherto not existedis tried. For example, control factors in the reducing depositionreaction of two-liquid mixture in liquid, used in the presentapplication, include largely a “solution control” and “reactioncircumstance control.” The former including (1) a reducing agent, (2) areducible substance and (3) a solvent, and (4) a “reaction circumstancecontrol” are main four elements. The element (1) is the direct controlmethod described above, but even if the element (1) can be controlled,it is substantially impossible to control the specific hydrogen contentas in the present application. In the elements (2) to (4), the hydrogenconcentration is not directly changed in the mixed solution, and thecontrol conditions are seemingly unlikely when a usual reaction state isconsidered. In the present application, the control of the hydrogencontent is realized in the following method, by operating the controlelements which appears impossible by conventional control methods.

(4) “Reaction Circumstance Control”

It has been found that the hydrogen content is increased by excluding aphysical stirring as much as possible, in other word, performing areaction quietly, at an interface of two kinds of liquid when the twoliquids are mixed; as a result, an amorphous phase can be formed allover (formation of an amorphous single phase). This finding makes itapparent that the hydrogen content in the extract can be controlled (canbe increased), and the formation of the amorphous phase can becontrolled (the formation of the crystal phase can be inhibited) bycontrolling the reaction circumstance (for example, physical dynamicenvironments such as stirring, a temperature, or a pressure) at orimmediately after the reaction, or controlling the change of thereaction circumstance (decreasing it as much as possible). Although itis seemingly an indirect control factor, which is the reactioncircumstance control of the deposition reaction, a certain kind of abinding reaction state of Fe and H, which has not hitherto been existed,is exhibited by creating the reaction circumstance, and it can be saidthat it is an extremely effective control method on the production of ananosize structure.

(2) Control of Hydrogen Content by Mainly Controlling Concentration ofReducible Substance

Seemingly, it seems to be a meaningless parameter control concerning thehydrogen content, but it is based on a finding of a phenomenon offorming shaped particles by a self-granulating reaction in whichspecific particles are formed or selected by largely changing aconcentration of, particularly, a reducible substance. It has been foundthat a specific binding reaction state is selected and the hydrogencontent is controlled by mainly changing the concentration of thereducible substance, whereby the amorphous structure is formed; as aresult, nanoparticles having specific composition, shape, size andstructure (self-granulating reaction particles) are formed. It can besaid that the method is an extremely effective control method on theproduction of nanostructure, because the selective control of the verydetailed binding reaction state is performed by mainly changing theconcentration of the reducible substance. In the reaction control, theeffect of (4) the reaction circumstance control is very large.

(3) Solvent

The minute reaction control, which is quite different from the usualreaction system, is performed as described above, and it has been foundthat an effect of a solvent is very large on the production of thenanoparticles or nanostructure. In the present application, for example,a certain kind of binding reaction state of H and Fe can be controlledby adding ethanol to a solvent of water. The addition of ethanolincreases the hydrogen content of the extracted structure, whereby thecomposition can be controlled (a content of a metal element isincreased), and a formless phase can be remarkably formed. In that case,similarly to (2), it can be attained by selective control of the bindingreaction state. This example seems also seemingly to be control of anunrelated parameter, but the hydrogen content can be controlled bycontrolling the certain kind of binding reaction state of Fe and H withthe solvent, and it can be said that the method is a very effectivecontrol method on the production of the nanostructure. In the reactioncontrol, the effect of (4) the reaction circumstance control is verylarge.

The specific control methods described above are methods by selectingthe certain kind of binding reaction state of a metal and hydrogen, andin particular, the control factors (2) and (3) are control methods inwhich the shape, composition, and crystal structure of a particle areselectively decided by selection of the bound state, and properties(physical properties) of a resulting product are decided according towhich bound state is selected or exhibited, and thus stepwise change inthe nature, which is observed in conventional reactions, may not beobserved. The control factor for selecting or exhibiting the bound stateis not also changed stepwise, and a specific state may be selected in acertain range or at a certain threshold value or more, and specificnanoparticles or nanostructure may be formed.

In this application, it makes apparent that when the bound state of themetal-based element and hydrogen is a compound or cluster having a mixproportion of M_(m)H wherein m is an integer and m≥3 (referred to as a“hydrogen cluster” or “H cluster”), physical properties of themetal-based structure, nanoparticle, or cluster can be made particularlystable. In addition, the bound state can be selected by controlling them number of the H cluster, and, for example, it makes clear that as theshape of nanoparticles, the shaped particle size, the formation of theformless phase, the composition of the metal-based element, and thecrystal structure can be extremely precisely controlled.

(3-1) Step of Reducing Reducible Substance

The metal-based structure according to one embodiment of the presentinvention is a structure obtained by reducing a reducible substance; inother words, it is a structure obtained by reducing a reduciblesubstance, which is a specific substance which can be reduced. The“structure obtained by reducing a reducible substance” has the samemeaning of the “structure obtained by reducing a substance capable ofbeing reduced.” In the instant specification, the “reducible substance”refers to a substance which can be reduced and has reducibility. It canbe expressed as a “substance capable of being reduced” and it includes asubstance containing a metal-based reducible component, which containsat least one of a metal element and/or a semi-metal element. The“metal-based reducible component” can be expressed as a “metal-basedcomponent capable of being reduced” and it means a metal substance whichcontains a reducible component (component capable of being reduced),which is capable of forming a metal-based reduced substance (including asemi-metal) whose valence is 0 by receiving electrons, which is asubstance relatively oxidized. Specifically, the metal-based reducedsubstance may include metals and/or semi-metals, and in this case, themetal-based reducible component may include positive ions of metalsand/or semi-metals. If the explanation is made using the examplesdescribed above, the metal-based reducible component are exemplified bypositive ions of metals and/or semi-metals, hydrated ions of thepositive ions described above, substances containing an oxo acid ion(such as molybdate ion) containing the positive ion described above, andcoordination compounds (such as ferrocene) containing the positive iondescribed above.

A substance providing the reducible substance may include metals saltssuch as metallic chlorides, metallic sulfates, metallic acetates,metallic nitrides, and metallic perchlorates. These salts may be anonhydrate or a hydrate. The metal may be a ferromagnetism metal or anon-ferromagnetism metal. A metal ion contained in the metal salt may bea complex ion. Examples of the metal salt may include cobalt (II)acetate, cobalt (II) nitrate, cobalt (II) chloride, cobalt (II) sulfate,cobalt (II) perchlorate, nickel (II) acetate, nickel (II) nitrate,nickel (II) chloride, nickel (II) sulfate, nickel perchlorate,tetraamminenickel (II) chloride, iron (II) acetate, iron (II) nitrate,iron (II) sulfate, iron (II) chloride, iron (II) perchlorate,hexammineiron (II) chloride, copper (II) acetate, copper (II) nitrate,copper (II) sulfate, copper (II) chloride, copper (II) perchlorate,tetraamminecopper (II) chloride, silver (I) nitrate, bisamminesilver (I)chloride, lead (II) acetate, potassium tetrachloroplatinate (II), sodiumtetrachloroplatinate (II), potassium tetrachloroaurate (III), sodiumtetrachloroaurate (III), and the like.

One example of the methods for producing the metal-based structurecontaining hydrogen according to the present invention is characterizedby containing a reduction step of reducing a reducible substance, whichcontains at least one of metal element and/or semi-metal element, in aliquid containing at least one of hydrogen or a hydrogen-containingsubstance. The hydrogen-containing substance, which forms thehydrogen-based substance according to one embodiment of the presentinvention, may include hydrogen radical, hydrogen anion or hydride,substances containing the same. As the liquid in which thehydrogen-based substance exists, it can be exemplified by a case inwhich radicals, anions or hydrides exists, resulting from an interactionsuch as hydrogen bonding reaction with the solvent as another substance,in a solution containing the hydrogen-containing substance. It ispreferable that the hydrogen-based substance has a reducing property inorder to stably reduce the reducible substance.

When the metal-based structure according to one embodiment of thepresent invention has the nanopart structure, the metal-based structuremay be produced in a production method containing a step of reducing thereducible substance in liquid in which a hydrogen-based substance existsto form a nanopart structure, and a step of forming a metal-basedstructure containing multiple nanopart structures. In that case, thestep of forming the nanopart structure and the step of forming themetal-based structure may be defined as completely separated steps, ormay be continuous.

In the production method described above, the method for reducing thereducible substance is not specifically limited. The reduction may beperformed using a reducing substance, or may be performed byelectrolysis. The reduction by the electrolysis may specifically includeelectroplating and electrolysis of liquid. It may be performed bydecomposition reduction with heating. Specifically, a metal salt (suchas (potassium chloroplatinate (II)) is heat refluxed in an alcohol,whereby a colloidal metal can be formed. A photoreduction may beperformed. It is specifically exemplified by photoreduction of water.The reduction may be performed by electron donation (hydrogen donation).Specific examples of the method may include gas dissolution, and morespecifically bubbling of hydrogen gas in water, generation of hydrogenmolecules (H₂) from a reducing agent such as NaBH₄ (which is graded as aconcrete example of a reducing substance). An electron donor may besupplied in liquid. The substance may include metal such as Zn, as shownbelow, metal ions, and the like.

Cu²⁺+Zn→Cu+Zn²⁺

The “reducing substance” is a substance which can reduce the reduciblesubstance, and “to have a reducing property” means to have an actionwhich reduces the reducible substance.

The hydrogen-containing reducing agent may include hydrogenated boronsalts such as NaBH₄; hypophospites such as NaH₂PO₂ and H₃PO₂; hydrazine(H₂NNH₂); carboxylic acids such as oxalic acid (C₂H₂O₄) and formic acid(HCOOH); amines such as NH₂OH, N(CH₃)₃, and N(C₂H₅)₃; alcohols such asCH₃OH, C₂H₅OH, and C₃H₇OH, and the like. The reducing agent containingno hydrogen may include sulfites such as sodium sulfite (Na₂SO₃);hyposulfites such as sodium hyposulfite (Na₂S₂O₄), and the like. Thesubstance generating hydrogen gas may include hydrogenated boron saltsuch as NaBH₄. In order to promote the reaction of the reduciblesubstance with the hydrogen-based substance, the hydrogen-containingreducing agent is preferable. Further, a substance generating hydrogengas is preferable. The method may be performed in combination with amethod in which hydrogen gas is separately bubbled in liquid. When thereducible substance contains an element capable of forming aferromagnetic substance, particularly an Fe element, it may sometimes bepreferable to use a hydrogenated boron salt, particularly NaBH₄ as thehydrogen-containing reducing agent. In particular, there are cases inwhich the use thereof is preferable when the shape anisotropy or theshape of the metal-based structure is controlled.

When the metal-based structure is produced, it is considered that areaction, specifically oxidation, of the metal-based reduced substance,which is produced by the reduction, with another element can beinhibited by performing a method in which the reducible substance isreduced in liquid containing the hydrogen-based substance. It isconsidered accordingly that the reaction of the metal-based reducedsubstance with the other element is inhibited by reacting thehydrogen-based substance in the liquid with the other element prior tothe reaction of the metal-based reduced substance with the otherelement.

It is considered that the hydrogen in the metal-based structure, asdescribed above, influences on the composition of the metal-basedstructure, the formation of the formless phase, the crystal structure,and the like by binding reaction with the metal-based reduced substanceor formation of a solid solution.

From the above, the metal in the present invention is preferably a metalhaving an ionization tendency larger than that of hydrogen.

(3-2) Control of Composition of Metal-Based Structure, Hydrogen Contentand Formless Phase

In the production method above, the composition of the obtainedmetal-based structure containing hydrogen may be controlled bycontrolling one or more members selected from the group consisting of asolvent composition of liquid, an amount of the hydrogen-based substancein the liquid, a concentration of the hydrogen-based substance in theliquid, an amount of the reducible substance in the liquid, and aconcentration of the reducible substance in the liquid, and a reductiontime of the reducible substance in the liquid (in the instantspecification, which may sometimes be referred to as a “first group”).

In the production method above, the hydrogen content in the metal-basedstructure may be controlled by controlling one or more members selectedfrom the first group. The measurement method of the hydrogen content inthe metal-based structure is as described above.

In the production method above, the content of at least one of the metalelement and/or the semi-metal element, and the content of element otherthan hydrogen (in the instant specification, which may sometimesreferred to as the “other element”) in the metal-based structure may bedecreased by controlling one or more members selected from the firstgroup. The other element may specifically exemplified by oxygen.

In the production method above, the particle shape of the metal-basedstructure or the particle shape of the amorphous phase may be controlledby controlling one or more members selected from the first group.

In the production method above, whether or not the metal-based structurehas the formless phase may be controlled by controlling one or moremembers selected from the first group.

As the liquid containing hydrogen-based substance, a reducing agent maybe used. In that case, the amount and the concentration of the reducingagent in the liquid containing the hydrogen-based substance can be addedto the first group. The reducing agent includes a hydrogen-containingreducing agent, and the hydrogen-based substance may be produced fromthe hydrogen-containing reducing agent. The hydrogen-containing reducingagent may specifically include NaBH₄, LiAlH₄, and the like, as describedabove. The reducing agent other than the hydrogen-containing reducingagent may specifically include a bivalent Fe ion, a bivalent Sn ion, andthe like.

In the instant specification, the “solvent composition” means acomposition of liquid in which the reduction of the reducible substanceis performed. A degree of tendency of reduction of the reduciblesubstance in the liquid is controlled by the solvent composition,whereby the composition of the metal-based structure, in particular, thehydrogen content in the metal-based structure and the content of theother element in the metal-based structure can be controlled by thesolvent composition. The reason in which whether or not the metal-basedstructure has the formless phase can be controlled by the solventcomposition is not clear, but it is considered that hydrogen in themetal-based structure may influence on the generation of the formlessphase.

The particle shape of the amorphous phase can also be controlled by thesolvent composition.

The solvent containing the hydrogen-based substance contains preferablyat least one substance having hydrogen atoms capable of forming ahydrogen bind, in order to increase the controllability by the solventcomposition. The substance having hydrogen atoms may include substanceshaving at least one functional group selected from the group consistingof an O—H bond, an N—H bond, a P—H bond, and an S—H bond. Morespecifically, it is exemplified by water, alcohols, amines and thiols.There may be sometimes a tendency that when water is used as thesolvent, the obtained metal-based structure has a low hydrogen content;whereas, when an alcohol is used as the solvent, the obtainedmetal-based structure has a high hydrogen content. The tendency in whichthe obtained metal-based structure has a high hydrogen content may besometimes observed in a case in which water is used as a main solventand an alcohol is added thereto. The substance containing the hydrogenatom may be contained in the liquid as a mode other than one kind of thesolvent.

The amount of the hydrogen-based substance in the liquid and theconcentration of the hydrogen-based substance in the liquid alsoinfluence the easiness of the reduction of the reducible substance.Consequently, it is possible to control the composition of themetal-based structure, in particular, the hydrogen content in themetal-based structure and the content of the other element in themetal-based structure. The reason in which whether or not themetal-based structure has the formless phase can be controlled by theamount of the hydrogen-based substance in the liquid and theconcentration of the hydrogen-based substance in the liquid is notclear, but it is considered that the hydrogen in the metal-basedstructure influences the generation of the formless phase.

The amount of the reducible substance in the liquid and theconcentration of the reducible substance in the liquid also influencethe easiness of the reduction of the reducible substance. Consequently,it is possible to control the composition of the metal-based structure,in particular, the hydrogen content in the metal-based structure and thecontent of the other element in the metal-based structure. The reason inwhich whether or not the metal-based structure has the formless phasecan be controlled by the amount of the reducible substance in the liquidand the concentration of the reducible substance in the liquid is notclear, but it is considered that the hydrogen in the metal-basedstructure influences the generation of the formless phase.

When the concentration (FS) (mmol/kg) of the reducible substance iscontrolled as described below, a different H %, m number, shapedparticle, composition and crystal structure can be selectively formed(controlled).

When FS (Low range): 0.3≤FS<15, (preferably 0.3≤FS<3) mmol/kg issatisfied, an amorphous single phase having 0.4 at %≤H %<2.0 at %, an mnumber ≥31, 300B, and Fe₂B composition can be obtained.

When FS (High range): 3≤FS (preferably 150 or less), (preferably15≤FS≤150) mmol/kg is satisfied, a metal-based structure containing Feamorphous phase, or an Fe amorphous single phase, having 2.0 at %≤H %,an m number ≤30, and 100 F can be obtained.

Further, it is preferable to satisfy the following conditions.

The lower limit:hydrogen-containing substance concentration (H/+)>12mmol/kg, FS>0.3 mmol/kg.

Further, in order to stably advance the self-granulating reaction, it ispreferable that H/+ is less than 2000 mmol/kg and/or FS is less than 150mmol/kg. Further, in the FS (Low range) above, it is preferable that FS:0.3 mmol/kg or more and less than 14 mmol/kg, and H/+: 6 (NB:3) mmol/kgor more and less than 120 (NB:60) mmol/kg; more preferably that FS: 1.0mmol/kg or more and less than 3.0 mmol/kg, and H/+: 20 (NB:10) mmol/kgor more and less than 120 (NB:60) mmol/kg, in terms of the stableoperation.

Further, in the FS (High range) above, it is preferable that (S16) FS:15 mmol/kg or more and less than 150 mmol/kg, H/+: 30 (NB:15) mmol/kg ormore and less than 2000 (NB:1000) mmol/kg, and H: 0.05% by mass (2.7% byatom) or more, more preferably that H: 0.1% by mass (5.3% by atom) ormore, in terms of the stable operation.

The reduction time of the reducible substance in the liquid influences aproduction amount of the metal-based reduced substance, which isobtained by reduction of the reducible substance, and thus there arecases in which it is possible to control the composition of themetal-based structure, in particular, the hydrogen content in themetal-based structure and the content of the other element in themetal-based structure by the reduction time.

(3-3) Two-Liquid Mixing

The reduction of the reducible substance in the liquid may be performedby two-liquid mixing. The reduction of the reducible substance may beperformed by mixing first liquid (solution A) containing the reduciblesubstance with second liquid (solution B) containing at least one of thehydrogen-based substance and a substance capable of producing thehydrogen-based substance. In that case, it may be sometimes preferableto gradually mix the second liquid with the first liquid, whereby theconcentration change of the reducible substance can be decreased as muchas possible. The mixing speed of the second liquid to the volume of thefirst liquid is preferably adjusted to 50 volume %/second or less, morepreferably 0.01 volume %/second or more and 10 volume %/second or less.In order to more stably perform the reaction, the speed may bepreferably adjusted to 0.05 volume %/second or more and 1 volume%/second or less.

In that case, the composition of the metal-based structure can becontrolled by controlling one or more members selected from the groupconsisting of an amount and a concentration of the reducible substancein the first liquid, an amount and a concentration of the hydrogen-basedsubstance in the second liquid, an amount and a concentration of thesubstance capable of producing the hydrogen-based substance, and avolume ratio, which is a ratio of the volume of the second liquid to thevolume of the first liquid (in the instant specification, which maysometimes be referred to as a “second group”). The hydrogen content andthe content of the other element in the metal-based structure can becontrolled by controlling one or more members selected from the secondgroup. Whether or not the metal-based structure has the formless phasecan be controlled by controlling one or more members selected from thesecond group.

The second liquid may contain the reducing agent. The reducing agentcontains the hydrogen-containing reducing agent, and the hydrogen-basedsubstance may be produced from the hydrogen-containing reducing agent.In that case, the reducing agent corresponds to one kind of thesubstances capable of producing the hydrogen-based substance. When thesecond liquid contains the reducing agent, the amount and theconcentration of the reducing agent in the second liquid can be includedin the second group.

With respect to the composition of the metal-based structure, hydrogencontent in the metal-based structure, the content of the other element,and whether or not the metal-based structure has the formless phase,there is a tendency in which the content of the metal component in themetal-based structure and the hydrogen content are increased and thecontent of the other element such as oxygen is decreased with theincrease of the volume ratio.

The hydrogen content, the particle shape of the amorphous phase, and thecomposition of the amorphous phase can be controlled by adjusting thekind and the concentration of the solvent in the solution A and/or thesolution B.

Here, the concentration of the reducible substance in the A solution maybe a value in the terms of the metal and/or the semi-metal element.Further, the concentration of the reducible substance is exemplified bya positive ion concentration of the metal and/or the semi-metal. In acase of the metal-based structure containing, as a main component, themetal element, the concentration is exemplified by a positive ionconcentration of the metal.

(3-4) Addition Dropwise and Stirring (Reaction Circumstance Control)

The first liquid and the second liquid may be mixed by adding dropwiseat least one of the first liquid and the second liquid to the other ofthe first liquid and the second liquid. In that case, there is aninterrelationship between the volume ratio and the reduction time of thereducible substance. At that time, preferably, it may be possible todecrease the concentration change of the reducible substance as much aspossible, by adding dropwise the second liquid to the first liquid. Thedropwise addition speed of the second liquid in that case is preferablyadjusted to 0.001 mL/second or more and 50 mL/second or less. In orderto more stably perform the reaction, the speed may be preferablyadjusted to 0.01 mL/second or more and 5 mL/second or less. With thedropwise addition speed, it may be sometimes preferable that a dropwiseaddition operation in which the liquid is added dropwise to other placesby using multiple nozzles, whereby the dropwise addition operation timeis substantially shortened.

The concentration fluctuation of the reducible substance at the dropwiseaddition can be decreased by adding the reducing component to thesolution of the reducible substance, whereby the metal-based structurecan be stably formed.

It is also preferable to suppress application of a mechanical externalforce to deposited particles as much as possible by advancing thereaction performing a stirring operation, or the like (performing thecontrol without inhibition of the advance of the self-granulatingreaction).

The formation of the amorphous phase can be promoted by the “quietreaction” as described above; in other words, the H % content can becontrolled and the formation of the amorphous phase can be controlled bythe “reaction circumstance control.” Further, the m number of theclusters can be controlled, whereby the metal-based structure and thephysical properties of the nanoparticles can also be stably formed. Thereaction circumstance control is also an important factor concerning theself-granulating reaction, and the physical properties of the shapedparticle can be stably formed by “quiet reaction,” as in the formationof the amorphous phase.

The reaction circumstance control is to control the change during thereaction in the comparison with a standing state before the reaction(difference from the standing state), and is a very important controlfactor for obtaining the pre-determined effects of the presentapplication. When the change of the pressure [Pa], temperature [K], andmagnetic field effect [T] of the solution during the reaction arecontrolled to values sufficiently small (<1E(−4)), for example, when thetemperature is a normal temperature, the pressure is a normal pressure,and there is no change in the magnetic field effect (a permanent magnetis fixed) as in Examples, the “reaction circumstance control” isperformed by controlling amounts of change in the “volume factor” andthe “stirring factor” to specific values or less. The “volume factor”refers to a rate of increase in the volume by mixing: V2/V1/time[1/second], or an amount of increase in the volume by mixing: V2/time[mL/second]. The “stirring factor” refers to a revolution speed of arotor (S) [1/second], or the maximum speed of the rotor (Sv)[mm/second], wherein in a case of vibration of the solution, it is thevibration number [1/second], and in a case of movement of the solution,it is the maximum moving velocity [mm/second] (the moving velocity is avelocity to a container). When there is a steady flow, it is a relativevelocity [mm/second] to the stead flow. S and Sv are appropriatelyconverted to each other. Sv=2πrS (r: a radius of the rotor).

(3-5) Threshold Values T of Hydrogen Content and m Number

The binding reaction state of the metal element or semi-metal elementand H, the metal element and H, or the Fe and H as shown in Examples, isselectively controlled by changing, in addition to the “reactioncircumstance control,” the “solution control,” in particular, aconcentration of the reducible substance (FS concentration); as aresult, the hydrogen content in the metal-based structure, nanoparticleor cluster is controlled, and the specific mix proportion (the m number)is controlled. Further, the particle shape, i.e., the hydrogen content,composition and crystal structure, shape and size of the particle, canalso be controlled.

In the present application, the existence of a “threshold value T of aconcentration of the reducible substance” for controlling the hydrogencontent, or controlling the m number has been found. (Example 1-11) At athreshold value T or more, the H % is controlled to 2.0 at % or more andm controlled to m≤30 or less, and a structure, nanoparticle, or cluster(metal H cluster), formed of the metal element or the metal singleelement (Fe) can be formed. (Example 1-12) At a less than thresholdvalue T, the H % is controlled to less than 2.0 at % and m is controlledto m≥31, and a metal-based structure formed of an Fe₂B composition canbe formed. The “threshold value T can be controlled” by the solventcontrol. (Example 1-7) The threshold value is decreased by adding analcohol (or ethanol) to a solvent, and at a threshold value T or more,the H % is controlled to 2.0 at % or more and m is controlled to m≤30,or the H % is controlled to 9.0 at % or more and m is controlled to m≤8,and a formless phase in which shaped particles 300B are mixed is formed,and a structure formed of the metal element, or the structure formed ofthe single element metal (Fe) are obtained. In Examples in the presentapplication, when the solvent is water, the threshold value is 0.21% ofthe saturated concentration, or 3 mmol/kg, and when an alcohol is added,the threshold value is decreased to 1/10 and is 0.3 mmol/kg. The amountof the alcohol added of 1% by weight or more is effective. When thesolvent is ethanol, the effect may sometimes be further increased.

When the concentration (metal ion concentration) of the reduciblesubstance is adjusted to the threshold value or more, a structure,nanoparticle, or cluster (“metal H cluster”) may sometimes be producedwhich consists of the metal element, or the single element metal (Fe),without the semi-metal. The threshold value relates to the clustercomposition (metal element) and does not necessarily correspond to theparticle shape.

There is a case in which the size of the shaped particle does not changedepending on the kind of the solvent. In Examples in the presentapplication, the addition of the alcohol to the solvent decreased thethreshold values of the H % and the m number, but did not change thesize of the shaped particle.

In the structure, nanoparticle or (metal) cluster formed of the metalelement, or the single element metal (Fe), formed at the threshold valueor more, a product having a lower the H % content and a larger the mnumber is formed with increase of the concentration of the reduciblesubstance, and the H % content and the m number, respectively,negatively and positively correlate to the concentration of thereducible substance; in other words, the tendency is observed in whichthe metal component is increased and the hydrogen content is decreasedin the structure with increase of the concentration of the reduciblesubstance.

(3-6) Control of Formation of Amorphous Phase, Particle Shape, Formationof Formless Phase, and Composition of Metal-Based Structure by Controlof Hydrogen Content

Seeing the above from the viewpoint of the control of the hydrogencontent, it can be said that at least one of the following (i) to (iii)can be controlled by controlling the hydrogen content to the wholemetal-based structure;

(i) To control the formation of the amorphous part;(ii) To control the particle shape; and(iii) To control the composition of the metal-based structure.

(3-6-1) Formation of Amorphous Phase by Control of Hydrogen Content

As described above, the present application provides the method forcontrolling the formation of the amorphous phase of the metal-basedelement, metal element, and single element metal, which is difficult tocause not only in a usual equilibrium reaction but also innon-equilibrium reaction such as a rapid solidification processing ofmelted metal. In particular, the formation of a compound of Fe with Hhas not been found, and the solid solution of H is known but it hashitherto been known that it is very difficult to form a combined stateof Fe—H. In the present application, the formation of the Fe amorphousphase containing hydrogen is deduced that the crystallization of Fe isinhibited by exhibiting a specific bound reaction state of Fe and H,which has not hitherto been considered, as a result, whereby the Feamorphous phase is formed by containing hydrogen. As the specific boundreaction state can be formed in Fe, which is the element having a verylow binding reactivity with H, the method for controlling the hydrogencontent and the method for controlling the formation of the amorphousphase of the present application are effective for other metal elementshaving a reactivity with H equal to or stronger than Fe.

(3-6-2) Control of Particle Shape by Control of Hydrogen Content

As described above, the particle shape can be controlled by controllingthe hydrogen content. The particle shape includes the formless phase.

(3-6-2-1) Control of Particle Shape, Self-Granulating Reaction, andMagnetic Field Progression

The shaped particle is formed by advance of the self-granulatingreaction in a manner in which the H % is controlled by the “reactioncircumstance control” in addition to the control of the concentrationof, in particular, the reducible substance in the “solution control.”The self-granulating reaction particles, accordingly, are formed byspontaneous growth of the aggregate until a specific character is formedby the self-granulating reaction. The formation of particles havinguniform characters by the above mechanism is the mark. In particular, asin the present application, the formation of the shaped particle formedof the amorphous phases (self-granulating reaction particles) is a veryspecific phenomenon, and the present application is based on the findingof the phenomenon and consideration of the control method. The effectsof the self-granulating reaction of the present invention areparticularly very high when the substance is formed of the metalelement, or the metal element single phase (Fe).

(3-6-2-2) Control of Particle Shape, Self-Granulating Reaction, ReactionCircumstance Control, and Cluster

The detailed mechanism of the self-granulating reaction is unclear, butit is considered that an effect of a surface area, because of thespecific uniform size, is one of the factors of self-control. Further,in a case of Examples in the present application, the particles have aspecific magnetism, because they are aggregated and aligned in amagnetic field, and the magnetism is one of the factors of self-control;in other words, there is a possibility in which a magnetically stableshape is formed. It is not observed that the particle size is changeddepending on the presence or absence of a magnetic action, and thus itis considered that the self-control by the magnetic property of theparticle itself may act.

In order to form the shaped particle by itself, i.e., to stably advancethe self-granulating reaction, the “reaction circumstance control” isimportant, and it is preferable that the control is performed so that“the reaction is quietly advanced,” as in Examples in the presentapplication.

Further, in order to stably form the shaped particles or to advance theself-granulating reaction, the formation of the structure, nanoparticle,or cluster having a specific mix proportion is very effective. When acompound or a cluster having a mix proportion of M_(m)H wherein m is aninteger and m≥3, or in addition to the above, a compound or a clusterhaving a specific m number wherein m≤30, which conforms to the regularpolyhedron rule, an ordered structure with a short range or compound isformed by the clusters, the self-granulating reaction is stably advanceddue to the specific crystal structure, composition, and magneticcharacteristics of the clusters or aggregates thereof, and shapedparticles having the uniform properties can be stably and effectivelyformed, as shown in Examples.

(3-6-3) Control of Composition by Controlling Hydrogen Content

When the H % of the metal-based structure is increased by “solutecontrol,” i.e., by changing the concentration of, mainly, the reduciblesubstance, a metal-based structure formed of the metal element, or thesingle element metal (Fe), containing no semi-metal element is obtained.When the “solvent control” is performed, i.e., the H % of themetal-based structure is increased by adding ethanol to water of asolvent, the same metal-based structure formed of the metal element, orthe single element metal (Fe), containing no semi-metal element isobtained.

The H % control and the composition control can be performed by adifferent operation, the “solute control” or the “solvent control”; inother word, it is possible “to control to the high purity metalcomposition formed of the metal element, containing no semi-metalelement, or the metal single element composition (Fe) by increasing theH %.” It is judged that “to control the composition by the H % control”and “to control to the high purity metal composition formed of the metalelement, or the metal single element composition (Fe) by the increase ofthe H %” are universal results, because the same cause and effectrelationship can be obtained by the different operation.

(3-7) Control of m Number

To control the m number is the control of the H %, and thus the m numbercannot be directly controlled by the H concentration during thereaction, for example, the H content in the reaction liquid as in thecase of the control of the H %. In the present application, in view ofthe circumstance, the same indirect control as in the H % control, istried, and it has been found that the m number can be controlled by the“reaction circumstance control” and the “solution control.”

The methods for controlling the m number (operation items andconditions) are as follows:

(1) “solution control”a threshold value of concentration of reducible substancem≤30 metal composition(2) “reaction circumstance control”dropwise addition/injection stirringm 20/30 formation of amorphous phase(3) “solution control”Solvent containing alcoholm 8 reduction of threshold value

As described above, it is understood that the method which is consideredto be the indirect control from the viewpoint of the control of thehydrogen content of the metal-based structure is the direct control fromthe viewpoint of the control of the m number. It is understood that themethod is a very reasonable control method from the viewpoint of thecontrol of the m number, and it can be said that it is a phenomenon inwhich the presence of the H clusters is demonstrated.

(3-7-1) Threshold Value of FS Concentration (Concentration of ReducibleSubstance)

It has been found that m≤30 or less can be obtained at a threshold valueof the FS concentration or more, whereby the H % is controlled to 2.0 at% or more and the metal H clusters are formed. Considering the case ofFe ion in Examples, it is interpreted to be an indirect control that theH % is controlled by the Fe ion concentration, and the H % is increasedby the increase of the Fe ion concentration from the viewpoint of the H%, but it is understood that Fe ion concentration is adjusted to thethreshold value or more, i.e., the Fe ion concentration is adjusted to aspecific value or more, to exclude elements other than Fe and H, wherebythe Fe—H cluster is formed from the viewpoint of the Fe ion, which canbe interpreted to be a direct control. When limiting to the a metal Hcluster having m≤30 or less, there is a positive interrelationshipbetween the FS concentration and the m number, that is, results of(Example 1-7) m=8 at FS_Low, and (Example 1-11) m=20 at FS_High areobtained.

From these results, according to the m number control by the reduciblesubstance concentration, a metal H cluster having m≤30 or less is formedat the threshold value of the reducible substance concentration or more,and when the metal H cluster is formed, a metal H cluster having a largem number can be produced by increasing the concentration of thereducible substance. From the above, the m number control by theconcentration of the reducible substance is interpreted to be the directcontrol. The method for controlling the m number by controlling the FSconcentration, accordingly, has a large effect, in particular, when thereducible substance contains the metal, further when the metal H clusteris formed.

(3-7-2) “Reaction Circumstance Control”

As described below, by control of a reaction circumstance, i.e., bycontrol of a mixing operation of (Example 1-11-2) a “dropwise addition”or (Example 1-14) an “injection mixing and stirring” when two liquidswere mixed, the m numbers were respectively controlled to m=20 and m=30.The m number is also controlled by a heat-treatment different from the“reaction circumstance control”; that is, the m number was respectivelycontrolled to m=20 and m=30 (Example 1-11-2) before the heat-treatmentand (Example 1-11-3) after the heat-treatment at 450° C. From DSCanalysis results of m=20 (Example 1-11, FIG. 56), two heat generationpeaks are observed, and a heat generation peak at a low temperatureside, about 320° C. is interpreted to be a measurement resultdemonstrating the structure change from an H cluster having an m numberof 20 to an H cluster having an m number of 30. From the results, it isinterpreted that the H cluster having an m number of 30 is energeticallymore stable than the H cluster having an m number of 20, the H clusterhaving an m number of 20, being at a higher energy level, is formed by“performing quietly” the deposition reaction, and the aggregates thereofform into the amorphous single phase.

On the other hand, it is interpreted that the H cluster having an mnumber of 30, which is at a lower energy level and is stable, is formedby performing the “injection mixing and stirring” or the heat-treatmentat 450° C. A mechanism in which the H cluster having an m number of 30,or the metal-based structure, which is aggregates of the clusters, formsan amorphous phase partly containing crystal phases, is not clear, butit is considered that the mix proportion of the metal atom is increasedby increasing the m number, and formation of crystal structure formed ofthe metal atom is appeared. Since the result of partly containing thecrystal phases, it is also interpreted that the H cluster having an m of30 is a more stable cluster at a lower energy level or forms a morestably assembled structure.

(3-7-3) Solvent

In Examples, it was found that the effect of decreasing the thresholdvalue of the concentration of the reducible substance is expressed bycontaining ethanol in the solvent. The threshold value is aconcentration value or more at which the metal H cluster can be formed,it is considered that in Examples, the presence of ethanol increases thebinding reactivity of Fe—H, and the metal H cluster is easily formedprior to reactions with other elements, and as a result, the metal Hcluster can be formed at a lower concentration of the reduciblesubstance, i.e., the effect of decreasing the threshold value isappeared. It is understood that the metal H cluster can be formed at alow concentration of the reducible substance by the presence of ethanol,as a result, the metal H cluster having a low content ratio of the metalatoms (the m number is small), i.e., having a large H %, is formed.

(3-7-4) Phenomenon Controlled by m Number (Physical Property)

The following items are controlled by controlling the m number (physicalproperty control by selection of cluster)

(i) H % control: m number(ii) Composition control: metal H cluster (m≥30)(iii) Amorphous phase control: amorphous single phase (m≥20) at metal Hcluster(iv) Particle shape control: particles by self-granulating reaction(m≥8), formless phase (m≤12)

(i) H % Control

The H % (at %) is decided by the m number, i.e., the mix proportion.

(ii) Composition Control

An H cluster containing the metal-based element, or metal element isformed at an m number more than 3. A “metal H cluster” formed of metalelement, or the metal single element is formed at m≤30; that is, thecomposition of the metal-based element is controlled. In Examples,structures, nanoparticles, or cluster, having an Fe₂B composition,formed of the metal and the semi-metal, and containing the metalelement, were formed at m≥31. Structures, nanoparticles, or cluster,formed of the metal element or the single element metal (Fe), wereformed at m≤30.

(iii) Amorphous Phase Control

In the “metal H cluster” having m≤30, the crystal structure or theamorphous structure is controlled by the m number. In Examples, anamorphous phase is formed at m≤30. A partly crystallized amorphousphase-containing structure is obtained at m=30. An amorphous singlephase is formed at m≤20. There is a case in which the amorphousstructure varies depending on the m number even if they have the sameamorphous single phase structure. In Examples (comparison of Example1-11-2 and 1-7), because there is a difference in DSC analysis results(FIG. 56/FIG. 54) between the case of m=20 and the case of m=8, althoughin both cases the amorphous single phase is formed, the difference inthe amorphous structure is confirmed. It is considered that thedifference in the amorphous structure is caused by the difference in them number, i.e., the difference in the cluster structure.

(iv) Particle Shape Control (Shaped/Formless)

There is a case in which the shaped particle formation is controlled bythe m number. It is particularly preferable that the shaped particlesare formed by the self-granulating reaction. In Examples, shapedparticles were formed by the self-granulating reaction at m≥8, and aformless phase formed of the amorphous phase was formed at m≤12 furtherat m≤8. A transitive state in which the shaped particles and theformless phases are mixed was obtained at m=8. Further, the shapedparticles may sometimes be controlled by the m number. In Examples(Example 1-7), self-granulating reaction particles having a particlesize of 500 nm or less and formed of the amorphous single phase wereobtained at m≥8. Further, (Example 1-11-2) self-granulating reactionparticles having a particle length of less than 175 nm and formed of theamorphous single phase were obtained at m≥12, further at m≥20. Althoughthese self-granulating reaction particles are both has the amorphoussingle phase structure, since there is a difference in DSC analysisresults (FIG. 54/FIG. 56), the difference in the amorphous phasestructure is confirmed. It is considered that the difference in theamorphous structure is caused by the m number, i.e., the difference inthe cluster structure.

(3-8) Post-Step

Steps after the formation of the metal-based structure in liquid are notparticularly limited. The deposited substance in the liquid may besubjected to an aggregation step, a washing step, and a drying step inthis order, or may be subjected to a washing step, an aggregation stepand a drying step in this order.

The aggregation step may include a method in which the depositedsubstance is aggregated by applying a magnetic field to the liquid, andaggregates are recovered. According to this method, it is effective thatwhen targets having the nanostructure are aggregated, the aggregationwork is performed by applying the magnetic field. In particular, theaggregation by the magnetic field action is very useful in order tomaintain the fine structure of the metal-based structure. It is alsoeffective to utilize the difference in a sensitivity to the magneticfield to perform selection and recovery. When the target is aferromagnetic substance, this method is particularly effective becausethe selection and recovery of the ferromagnetic substance, and theremoval of unnecessary oxide components can be easily performed. Inaddition, it is effective that after the aggregation of the magneticfield aggregation, the following washing is performed in terms of themaintenance of the nanostructure and removal of unnecessary componentsto obtain a high purity.

The washing work is a very important process on the removal of impuritycomponents. It is preferable the washing is performed using a solventcapable of dissolving the unnecessary components. It is particularlypreferable to use washing liquid containing the component contained inthe solvent used in the reduction reaction. For example, in Examplesdescribed below, in order to remove ion components such as SO₄ ²⁻ andoxides, washing step of washing with water three times and washing withethanol three times was performed. In Examples, water and ethanol areused as the solvent used in the reduction reaction.

It may sometimes be good that the target, which is aggregated by themagnetic field action, is washed in the aggregated state, whereby thewashing can be performed without destroying the fine structure of themetal-based structure having the wire shape. When the target is theferromagnetic substance, this method is further effective, because theselection can be performed utilizing the difference in the sensitivityto the magnetic field. For example, it is possible that unnecessaryoxide components having a weak sensitivity to the magnetic field (forexample, iron oxides and boron oxides) are separated and they areremoved with washing in a state in which the metal-based structuresformed of Fe are aggregated, which is effective to obtain a high purity.

There are cases in which a more effective separation and removal washingcan be performed by performing the washing after the aggregation stepusing the magnetic field. It may sometimes be effective that the washingstep is divided to several times, and washing works are performed usingdifference solvents. A mixed solvent may be used. In the final washingstep, it is advantageous to use a solvent having a lower vapor pressure,to increase the efficiency in a subsequent drying step. It is good toperform the drying step in a manner in which the target is washed withwater, followed by alcohol, and then the drying step is performed, as inExamples described below. Ethanol is particularly effective.

4. Production Method of Metal-Based Structure Containing MagneticSubstance (4-1) Production Method Using No Nucleating Agent

It is advantageous that the nanoparticles are formed using a liquidphase reduction method, because it is preferable to form thenanoparticle in the liquid and to form the metal-based structure in theliquid, in order to enhance the easiness of handling of thenanoparticles. At that time, according to a conventional technique, amanner in which a reducible substance is put in liquid, a nucleatingagent, in addition to a reducing agent, is also put in the liquid,metal-based reduced substances are deposited from a reducible substance,using a component formed from the nucleating agent as a nucleus, andthey are grown to form nanoparticles has been generally performed inorder to stably advance the formation of the nanoparticles.

According to the method as above, however, components derived from thenucleating agent are essentially incorporated into the nanoparticles andthus it is essentially impossible to produce a material having excellentuniformity in terms of the composition and the crystallography, and theexpression of original physical properties may sometimes be inhibited.

The present inventors have studied a method for producing nanoparticlesand metal-based structures in liquid without using the nucleating agent,which is actually essential in the conventional technique, in the liquidphase reduction.

When the nucleating agent is not used, a process of growth ofnanoparticles from metal-based reduced substances formed in the liquidphase reduction method is unstable, and it is very difficult to producethe metal-based structure having the pre-determined shape characteristicwith a high repeatability. It is practically natural to use thenucleating agent in the conventional technique, because of the lowcontrollability in the growth process of the nanoparticles.

As a result of the present inventors' painstaking studies, however, ithas been clear that even if the nucleating agent is not used, when thereducible substance contains elements capable of forming a magneticsubstance, preferably a ferromagnetic substance, a metal-based structurehaving a different shape characteristic can be produced with a goodrepeatability by controlling the following elements, upon the reductionof the reducible substance in the liquid.

(4-2) Element (4-2-1) (Element-1) Solvent Composition

As described above, in the instant specification, the “solventcomposition” means the composition of the solvent in the liquid in thereduction step. The solvent may be a polar solvent or a non-polarsolvent. When the reducible substance is a polar substance such as ions,it is preferable that at least a part of the reducible substance isdissolved in the liquid, and thus the solvent is preferably a polarsolvent capable of dissolving the reducible substance. The polar solventmay be protonic or aprotonic. The protonic polar solvent may includewater, alcohols, thiols, acids, and the like. The aprotonic polarsolvent may include ketones, ethers, sulfoxides, and the like.

The shape of the produced metal-based structure may sometimes be changedby changing the composition of the solvent. For example, when a solventformed of water is used and other conditions are set the same as eachother, a metal-based structure having a nanopart structure with arelatively high aspect ratio may be easily obtained. On the other hand,the aspect ratio of the nanopart structure forming the metal-basedstructure may sometimes be decreased by increasing the alcohol contentin the aqueous solvent.

It can be considered that behavior of the metal-based reduced substancein the liquid in a process in which the nanopart structure is producedfrom the metal-based reduced substance, obtained by the reducing thereducible substance, and behavior of the nanostructure in the liquid ina process in which multiple structures corresponding to the nanopartstructure (in the instant specification, which may sometimes be referredto as a “nanostructure”), when a part of the metal-based structure isformed, are bounded to each other to form the metal-based structurevaries by the change of the solvent composition.

In particular, the solvent influences physically and chemically themovement of the reduced substance in the liquid so as to provide theshape anisotropy to the nanopart structure, the binding and aggregationof the reduced substance to each other, and the movement of thenanostructure in the liquid so as to provide the shape anisotropy to themetal-based structure; as a result, the solvent composition largelyinfluences the shape characteristic of the metal-based structure.

(4-2-2) (Element-2) Starting Material Concentration

In the instant specification, the “starting material concentration”means a concentration of the reducible substance in liquid in thereduction step, which is a step in which the reducible substance in theliquid is reduced to produce a metal-based reduced substance containinga reduced substance formed by reducing a reducible component containedin the reducible substance in the liquid. The starting materialconcentration is one of the elements influencing the basic shape of themetal-based structure and the nanostructure forming the above. As shownin Examples, when the starting material concentration is adjusted to athreshold value or more, a fibrous nanostructure is easily obtained. Onthe contrary, when the starting material concentration is a thresholdvalue or less, a bead-shaped nanostructure is easily obtained. Thethreshold value varies by a magnetic field strength for thesolidification, explained next, and when the magnetic field strength forthe solidification is high, the threshold value tends to be decreased.

It is considered that the control of the dispersion concentration of themetal-based reduced substance obtained by reducing the reduciblesubstance (in the instant specification, which may sometimes be referredto as a “reduced substance dispersion concentration”) in the liquid isrealized by changing the starting material concentration. It isconsidered that the increase of the reduced substance dispersionconcentration to a pre-determined threshold value or more is realized byadjusting the starting material concentration to a pre-determinedthreshold value or more, and in that case, a metal-based structurehaving an appearance similar to that of a yarn or web, which is anaggregate of fibers, is obtained, as shown in Examples. On the otherhand, when the starting material concentration is less than apre-determined threshold value, a metal-based structure having a shapeobtained by connecting multiple bead-shaped nanostructures is obtained.

The threshold value of the starting material concentration variesdepending on the magnetic field strength for the solidification, andwhen the magnetic field strength for the solidification is high, thethreshold value of the starting material concentration tends to bedecreased. From this, it is considered the magnetic property of themetal-based reduced substance influences whether the metal-basedstructure has a nanopart structure based on the nanostructure having ashape similar to a fiber or has a nanopart structure based on abead-shaped nanostructure.

It can be considered that the nanostructure having a structure like thefiber has such a shape so that the metal-based reduced substance hasgrowth anisotropy; that is, when the metal-based reduced substanceparticles collide to each other based on an isotropic motion such asBrown motion in a state in which the fine particles of the metal-basedreduced substance are dispersed, a nanostructure, obtained by growingthe metal-based reduced substance, can be expected to be an isotropicshape, but a bias is grown in a certain direction when the metal-basedreduced substance is grown, thus resulting in the structure having theshape anisotropy, like a fiber.

(4-2-3) (Element-3) Magnetic Field Strength for the Solidification

In the instant specification, a “magnetic field strength for thesolidification” means a strength of the magnetic field applied to asubstance existing in liquid, in the reduction step and/or asolidification step in which the metal-based reduced substance, producedin the reduction step, is grown to obtain a metal-based structure. Themagnetic field strength for the solidification may vary temporally, thatis, it may be exemplified by a case in which the magnetic field strengthfor the solidification is low in the reduction step, and the magneticfield strength for the solidification is high in the solidificationstep, or a case in which the magnetic field strength for thesolidification is low even in the solidification step, or some timeelapses, and after that the strength is increased. The magnetic fieldstrength for the solidification is one of the elements influencing thebasic shape of the metal-based structure, and the nanopart structure ornanostructure forming the above, in addition to the starting materialconcentration described above. When the magnetic field strength for thesolidification is high, a metal-based structure formed by binding thenanopart structures or nanostructures easily forms a shape which isobserved as a shape having a part structure with a high aspect ratio inan observation visual field with a certain range (for example, 10 μm×10μm).

The reason in which the anisotropy is caused in the growth of themetal-based reduced substance by increasing the starting materialconcentration is not clear, but it is considered that a magneticproperty influences the metal-based reduced substance. It is considered,accordingly, that the metal-based reduced substance has paramagnetism orsuperparamagnetic, hardly causes a leakage field, and has a lowsensitivity to an outer magnetic field at an initial stage of thegeneration; whereas, it turns to a nanostructure having a singlemagnetic domain structure capable of causing the leakage field byappropriate growth. Hereinafter, the nanostructure may sometimes bereferred to as the “magnetized nanostructure.” Once the nanoparticle hasthe magnetized nanostructure having the single magnetic domainstructure, the sensitivity to the outer magnetic field is alsoincreased, and thus a magnetic interrelation action is easily causedwhen the magnetized nanostructure approaches the magnetizednanostructure. In addition, the interrelation action with themetal-based reduced substance approaching the magnetized nanostructureis also influenced by the leakage field of the magnetized nanostructureto have the anisotropy. As a result, another magnetized nanostructurebinds to the magnetized nanostructure in a direction along a singlemagnetic domain, or a ratio of the metal-based reduced substance boundalong the direction of the single magnetic domain is increased, wherebya bias is caused in a growing direction of the nanostructure, and thenanostructure having the growth anisotropy is formed.

Considering as above, some explanation can be applied to the loweredthreshold value of the starting material concentration, which decidesthe shape of the metal-based structure, by increasing the magnetic fieldstrength for the solidification, thereby to obtain the filament shapeeven if the starting material concentration is relatively low. Thenanostructure having a measurable magnetic anisotropy in the middle ofthe growth to the single magnetic domain is more easily aligned alongthe outer magnetic field with the increase of the magnetic fieldstrength for the solidification. It is considered that when the magneticfield strength for the solidification is high, accordingly, the startingmaterial concentration is low, and thus even a nanostructure having arelatively small diameter has the growth anisotropy, and is easily grownto a fibrous shape.

As fiber forming a web, which is an aggregate of fibers, is classifiedinto a staple (short fiber) and a filament (long fiber) based on thedifference in the length, the metal-based structure having the web shapecan also be classified, as above, into a structure having a staple webshape based on the short fiber and a structure having a filament webshape based on the long fiber.

As one of the elements deciding that the metal-based structure havingthe web shape has either shape, the magnetic field strength for thesolidification is recited. When the magnetic field strength for thesolidification is less than a threshold value, the metal-based structurehaving the staple web shape is obtained, and when the magnetic fieldstrength for the solidification is a threshold value or more, themetal-based structure having the filament web shape is obtained. Themetal-based structure having the filament web shape is obtained byinterlacing or binding multiple filament-shaped (long fiber) metal-basedstructures, floating in the liquid.

The presence of the threshold value of the magnetic field strength forthe solidification, deciding the kind of the web shape (stapleweb-shape/filament web shape) may be easily understood, if supposing thenanostructure having the structure like the fiber. When the magneticfield strength for the solidification is strong, a percentage of thefibrous nanostructures existing in the liquid along the outer magneticfield is increased. Thus, the connection of the nanostructures to eachother is easily caused in a direction along the outer magnetic field,and consequently, it is easy to obtain the filament metal-basedstructure having a long fiber length.

On the other hand, when the magnetic field strength for thesolidification is weak, a percentage of the nanostructures existing inthe liquid and existing along the outer magnetic field is smaller thanthat in the case in which the magnetic field strength for thesolidification is strong. Thus, a possibility in which the long axisdirection is oriented and the length in the long axis direction isprolonged is decreased when the nanostructures are connected to eachother, and consequently the metal-based structure having the staple webshape obtained by interlacing the short fibers is easily obtained.

When the metal-based structure having the filament shape is used,linearity may sometimes be important. In such a case, as the elementimproving the linearity of the filament, the magnetic field strength forthe solidification and the work time of the magnetic field are recited.With respect to these elements, the production conditions may beadjusted, observing the shape of the obtained metal-based structure. Forexample, as shown in Examples, when the reducible substance contains theferromagnetic substance, or Fe, a magnetic field action caused by aferrite magnet or a magnet field action more than that, preferably amagnetic field action caused by a neodymium magnet may be applied in 5minutes after the finish of the dropwise addition of the reducing agent.When the time until the magnetic field action is applied is prolonged orthe magnetic field strength is relatively decreased, a metal-basedstructure having a shape with a low linearity based on the staple can beeasily obtained.

It is possible that the nanostructure or magnetized nanostructure andthe nanopart structure or metal-based structure are grown so as to haveat least one of the pre-determined particle size and the pre-determinedmagnetic characteristics, and then the magnetic field strength for thesolidification is increased. Here, the pre-determined magneticcharacteristic means a property providing the reactivity to the magneticfield and forming the structure by the movement and/or the alignment inthe magnetic field. For example, it is exemplified by magneticsusceptibility, to have the single magnetic domain structure, to havethe ferromagnetism, to have the paramagnetism, to have thesuperparamagnetism, and the like.

When the metal-based structure contains the ferromagnetic substance,particularly Fe, the particle size is preferably adjusted to from 50 nmto 500 nm, more preferably from 90 nm to 400 nm. Further, it ispreferable that the particle size is adjusted to the following range.

When the metal-based structure has the shape based on the staple orfilament shape, the particle size is preferably adjusted to from 50 to250 nm, more preferably from 100 to less than 175 nm.

When the metal-based structure has the shape based on the bead shape,the particle size is preferably adjusted to from 150 to 500 nm, morepreferably from 175 to 350 nm.

With respect to the magnetic field strength for the solidification,cases in which the magnetic field strength for the solidification isincreased before the growth or before the deposition are included, eventhe metal-based structure is in the middle of the growth. Specifically,it is possible that the size or the magnetic characteristics aregradually changed in the growth process, and a desired substanceresponds to the magnetic field action to selectively form themetal-based structure.

The metal-based structure having either the staple web shape or thefilament web shape can obtain a shape capable of functioning as athree-dimensional mesh, by appropriately setting a existence density ofthe interlaces or the bonds.

When the magnetic field strength for the solidification is a thresholdvalue or more, the metal-based structure having the shape obtained byconnecting multiple bead-shaped nanoparticles, obtained when thestarting material concentration is low has a shape bead wire shapeobtained by aligning and connecting multiple nanoparticles having beadshape. A metal-based structure having the web shape can be obtained bybinding or interlacing multiple metal-based structures having the beadwire shape and floating in the liquid. The metal-based structure havingthe web shape can also have the shape capable of functioning as thethree-dimensional mesh.

On the other hand, when the magnetic field strength for thesolidification is less than a threshold value, a metal-based structurehaving a massive shape obtained by isotropically connecting multiplemetal-based structures having the bead shape can be obtained. Thethreshold value of the magnetic field strength for the solidificationshifts to a lower magnetic field side with increase of the startingmaterial concentration; in other word, when the starting materialconcentration is high, the metal-based structure having the bead wireshape can be easily obtained even if the magnetic field strength for thesolidification is low.

The magnetic field strength for the solidification may be controlled sothat the strength temporally varies. For example, there are cases inwhich the shape of the obtained metal-based structure is different fromeach other between a case in which the magnetic field strength for thesolidification is increased from the start of the reduction step and acase in which the magnetic field strength for the solidification isincreased after the solidification step is advanced to some extent.Specifically, when the nanoparticle has the bead shape, the metal-basedstructure having the bead wire shape can be easily obtained byincreasing the magnetic field strength for the solidification from thestart of the reduction step, and it is difficult to the metal-basedstructure having the bead wire shape and the metal-based structurehaving the massive shape can be easily obtained by increasing themagnetic field strength for the solidification after some time elapsesfrom the finish of the reduction step.

Specifically explaining, as shown in Examples, when the reduciblesubstance contains Fe and forms the bead wire, it is preferable to applya magnetic field action caused by a ferrite magnet or stronger actionthan that, preferably a magnetic field action caused by a neodymiummagnet in 15 minutes after finish of the dropwise addition of thereducing agent. It is more preferable that the growth is performed whilethe movement is performed in a direction of a stronger magnetic fieldaction after the dropwise addition. In cases other than Examples, theproduction conditions may be adjusted observing the obtained shape.

When the reduced substance obtained from the reducible substance is amagnetic substance, the threshold value may be changed in accordancewith a degree of reaction with the magnetic field of the magneticsubstance.

When the magnetic substance shows a weak magnetic field reaction, adesired structure can be easily obtained by using a higher magneticfield strength. In the contrary case, suitably, an electricityconsumption and an apparatus strength can be inexpensively operated byusing a relatively weak magnetic field strength.

When a structure containing the ferromagnetic substance, particularly inwhich the reducible substance contains Fe, is produced, it is preferablethat the magnetic field strength is adjusted to 50 mT or more, morepreferably 100 mT or more. When the magnetic field strength is less than1000 mT, in a range of 300 to 1000 mT, from 300 to 800 mT, or from 300to 600 mT (more inexpensive), a permanent magnet can be used, and aninexpensive and stable operation can be preferably performed. Regardlessof the materials, the use of the permanent magnet is suitable for aninexpensive operation.

It may sometimes be preferable that there is a distribution in themagnetic field. Specifically, a case in which a magnet is set on a partof a bottom of a beaker, as performed in Examples, can be recited.According to the method in which the magnet is set on a part of thebottom of the beaker as above, the magnetic field strength is notuniform in the liquid, and has a dispersion in which the strengthbecomes weaker as it goes away from the magnet. This means that theparticles after the dropwise addition are grown while they move toward astronger magnetic field, and they are stuck to each other after theaggregation, which phenomenon is preferable. Before reaching themagnetic field strength necessary for sticking, preparatory steps of thenecessary growth and aggregation can be previously advanced. Inaddition, a large-scaled electromagnet apparatus may sometimes benecessary for applying the uniform magnetic field, but the method canutilize an apparatus which is more inexpensive than that.

In Examples, the following three kinds of magnets were used.

(1) Neodymium magnet-1 (a diameter: 15 mm, a height: 6 mm, a surfaceinductive flux: 375 mT)(2) Neodymium magnet-2 (a diameter: 30 mm, a height: 30 mm, a surfaceinductive flux: 550 mT)(3) Ferrite magnet-1 (a diameter: 17 mm, a height: 5 mm, a surfaceinductive flux: 85 mT)

Differences in the experimental results are not observed depending onthe two kinds of neodymium magnets described above.

For the movement and growth of the particles after the dropwiseaddition, a relative flow in the solution and the magnetic field may becontrolled. In that case, it is preferable to control a quiet flowwithout stirring or vibration at a flow rate of 100 mm/second or higher,or 500 mm/second or higher. The utilization of free convection orspontaneous sedimentation may sometimes be preferable.

(4-2-4) (Other Element)

In addition to the 3 elements described above, there are elementsinfluencing the shape of the metal-based structure. As the otherelement, an amount of the reducing agent, used for reducing thereducible substance is recited. Due to adding the reducing agent to theliquid containing the reducible substance, which is the liquid to becontained when the reduction of the reducible substance is advanced, theconcentration of the reducing agent in the liquid containing thereducing agent is apt to influence the shape of the metal-basedstructure. The concentration of the reducing agent may sometimesinfluence not only the shape of the metal-based structure but also thecomposition thereof (for example, the hydrogen content) and thecrystallographic characteristics (for example, when the reducedsubstance is Fe and the heat-treatment is performed for crystallization,the content ratio of αFe in the obtained metal-based structure). Adegree of the influence is related to the 3 elements described above,and is particularly highly related to the starting materialconcentration, and thus characteristics of a metal-based structureproduced may sometimes be effectively controlled by combination of theconcentration of the reducing agent and the starting materialconcentration.

(4-3) Shape of Metal-Based Structure

FIG. 1 is a view showing conceptually the classification of the shape ofthe metal-based structure in relation to the starting materialconcentration and the magnetic field strength for the solidification.

In a case shown in Example 1, two modes of the wire shape based on thefilaments and the bead wire shape based on the beads are generated, whenthe metal-based structure has a wire shape. The grown particle havingthe metal-based structure has at least two kinds of grown particlescorresponding to the two wire shapes. When a magnetic field is appliedto the specific grown particles, two kinds of modes of the wire shapeand bead wire shape are obtained by the influences of the magneticcharacteristics, the size (the whole size) of the grown particles. Thereducible ion concentration is dominant in the factor in which thenature of the grown particles is divided into two. However, the natureof the grown particles is divided into the two kind, although there is atransitive concentration region separating into two, and the sameconcentration is shown in the region by the magnetic field strength atthe deposition time or the growth time. From this, when the content ofthe reducible substance is 10 or more and less than 20 mmol/kg, thedifference in the mode described above easily appears due to themagnetic field strength; that is, the filament shape tends to be formedwhen the magnetic field strength is stronger. When the threshold valueof the mode change, in the terms of a content of the reducible substancewherein the reducible substance is the ferromagnetic substance, or Fe,is 3 mmol/kg or more, the filament shape is easily obtained, and fromthis viewpoint it is more preferably 20 mmol/kg or more, particularlypreferably 60 mmol/kg or more. When the reducible substance is theferromagnetic substance, or Fe, the bead wire shape is easily obtainedat less than 60 mmol/kg, and from this viewpoint it is more preferably10 mmol/kg or less, particularly preferably 3 mmol/kg or less. Thethreshold value for forming the filament shape tends to be decreasedwhen a magnet having a strong the magnetic field strength, i.e., theneodymium magnet, is used.

The metal-based structure obtained in the method described abovecontained the amorphous part in all of the 4 shapes shown in FIG. 1. Itis considered that the growth to the metal-based structure by bindingthe nanostructures to each other even applying a comparatively low outerforce such as the magnetic field or heat-vibration is related to theexistence of the amorphous parts in the metal-based structure; andfurther the effects thereof are enhanced by providing the bond of themetal-based structures through hydrogen and the inhibition of theformation of the oxidized layer due to the hydrogen-containingamorphous.

It is considered accordingly that the nanostructures also have theamorphous parts, the amorphous parts can be easily bound to each otherby a weaker outer force, compared to a crystalline substance, and theamorphous parts of the nanoparticles or nanostructure forming themremain in the metal-based structure in which they are bounded to eachother, thereby providing the amorphous parts in the metal-basedstructure.

5. Production Method of Metal-Based Structure with Formless Phase

The metal-based structure according to one embodiment of the presentinvention has the formless phase described above. The metal-basedstructure having the formless phase may sometimes be obtained when themetal-based structure, formed in a step which contains the reduction ofthe reducible substance in liquid, is taken out from the liquid. It canbe considered accordingly that the formless phase has already existed asanother structure in a state in which the metal-based structure is inthe liquid. There also is a possibility in which they have existed asthe grown particles having or capable of forming the formless phase, andthe formless phase is formed by taking them out from the liquid, or apart or all of the metal-based structures are melted by taking themetal-based structure out from the liquid, or by influences caused bythe drying or the heat-treatment step to change the structures thereof,thereby forming the formless phase. In that case, there is a possibilityin which the formless phases are generated so that they surround or takein the nanopart structure by disappearance of the liquid brought to intocontact with the nanopart structures or, particularly, the solvent.

As described above, the amount of the formless phase may sometimes bechanged by heating the metal-based structure taken out from the liquid(FIGS. 20, 22 and 23). Specifically, there is a case in which even ifthe formless phase is hardly observed when the metal-based structure istaken out from the liquid, the formless phase can be observed by heatingthe metal-based structure at about 50° C. When the heating temperatureis increased to about 200° C., the amount of the formless phase observedbecomes maximum. When the heating temperature is further elevated, theformless phase amount is rather decreased, and for example there is acase in which the amount formless phase observed at about 300° C. isapparently smaller compared to a case of about 200° C.

6. Production Method of Crystallized Metal-Based Structure

A metal-based structure which is crystallized, i.e., a crystallizedmetal-based structure, can be obtained by heating the metal-basedstructure according to one embodiment of the present invention to acrystallization temperature or higher. The temperature depends on thekind and the composition of the reduced substance.

The crystallization temperature can be confirmed by a DSC profile. Inthe metal-based structure in which the metal-based reduced substance isFe, a heat generation peak, which can be considered that it is caused bythe crystallization, is confirmed at about 460° C.

In the DSC profile, a heat generation peak may sometimes appear at atemperature lower than that of the peak which considered that it iscaused by the crystallization at about 460° C., specifically at about300° C. In a different case, an endothermic peak may appear at about380° C. What phenomenon causes this peak is unclear. When theendothermic peak on the lower temperature side is observed, there is acase in which the metal-based structure has the formless phase, and thusit is considered that there is some relationship between them. It isconsidered that, in the crystallization process of the metal-basedstructure having both the amorphous part and the hydrogen,crystallization is advanced by removal of hydrogen from the metal-basedstructure. It is considered that the endothermic change at about 380° C.is caused by the phenomenon accompanied with the removal of thehydrogen. The heat generation at about 300° C. may sometimes be observedin the metal-based structure having the filament shape, and it isconsidered that when the αFe single phase is obtained after thecrystallization, the heat generation at about 300° C. is caused by theformation of a metastable phase or quasicrystal phase formed of Fe orthe combination of Fe and hydrogen.

The metal-based structure has the nanopart structure, and when a cavityis defined by the nanopart structures, as described above, the volume ofthe cavity can be decreased or substantially lost by heating themetal-based structure at a temperature higher than the crystallizationtemperature (FIG. 27 to FIG. 29). When the cavity may adverselyinfluence macro physical properties of the crystallized metal-basedstructure, particularly the mechanical properties, the influences can bedecreased by appropriately adjusting the heating temperature.

The heating method in this case is not particularly limited.Pressurization may be performed instead of or in addition to theheating. At that time, the specific method of applying the pressure isnot limited. The atmosphere when the heating and/or the pressurizationis performed is not particularly limited, and it may sometimes bepreferable that the treatments are performed in vacuo or inert gas inorder to decrease effects of oxidation or the like. Alternatively, itmay sometimes be preferable to perform it in a reactive gas such ashydrogen, nitrogen or oxygen.

7. Production Method of Composite Structure

The metal-based structure according to one embodiment of the presentinvention has the nanopart structure, and there is a case in which acavity is defined by the nanopart structures. A composite structure canbe produced from the metal-based structure having such a cavity andusing other materials (additional substances) in a method describedbelow.

One of the production methods of the composite structure according toone embodiment of the present invention is a method in which anadditional substance is put in a cavity defined by the nanopartstructures of the metal-based structure having the nanopart structure toform a metal-based structure-additional substance mixture. The method ofputting the additional substance is not particularly limited. Theadditional substance is a powder and the metal-basedstructure-additional substance mixture may be formed by mixing thepowder with the metal-based structure. The metal-basedstructure-additional substance mixture may also be formed by performingan electroplating treatment to the metal-based structure in liquid todeposit the additional substance on the surface of the metal-basedstructure. Alternatively, the metal-based structure-additional substancemixture may be formed by putting the metal-based structure in liquidtogether with the reducible substance and a substance having a functionto reduce it, and depositing a substance obtained by reduction of thereducible substance or a substance based on the reduced substance(oxides, and the like) on the surface of the metal-based structure. Themetal-based structure-additional substance mixture may be formed byputting the additional substance on the surface of the metal-basedstructure in a dry process such as evaporation or spattering. When theadditional substance has a low melting point, the metal-basedstructure-additional substance mixture may be formed by immersing themetal-based structure in liquid formed of the additional substance (forexample, melted tin).

The thus obtained metal-based structure-additional substance mixture isheated as necessary, whereby the additional substance is stuck to themetal-based structure. The heating temperature depends on thecomposition and the shape of the metal-based structure and thecomposition and the shape of the additional substance. When an alloy isformed from the metal-based structure and the additional substance, theymay be stuck to each other even at a relatively low heating temperature.The substance may also be stuck to the structure even at a relativelylow heating temperature in a case in which the nanopart structure of themetal-based structure is sufficiently small and the additional substanceis also small.

If necessary, the volume of the cavity in the metal-based structure maybe decreased or substantially lost by adjusting the heating condition,specifically elevating the heating temperature. The heating temperaturebasically depends on the metal-based structure, but the additionalsubstance is melted at that temperature thus resulting in an interaction(alloying) with the material forming the metal-based structure, andconsequently the temperature at which the cavity substantiallydisappears may sometimes be different from a temperature at which thecavity substantially disappears in the metal-based structure alone.

For obtaining the composite structure from the metal-basedstructure-additional substance mixture, pressurization may be performedinstead of or in addition to the heating. At that time, the specificmethod of applying the pressure is not limited. The atmosphere when theheating and/or the pressurization is performed is not particularlylimited, and it may sometimes be preferable that the treatments areperformed in vacuo or inert gas in order to decrease effects ofoxidation or the like. Alternatively, it may sometimes be preferable toperform it in a reactive gas such as hydrogen, nitrogen or oxygen.

When the method described above is used, even a material which iselectrochemically base compared to the material forming the metal-basedstructure can be easily conjugated. When the metal-basedstructure-additional substance mixture or composite structure isobtained by reduction of the reducible substance in a state in which theadditional substance is dispersed in liquid, there is a risk that themetal-based structure is not formed, or it is difficult to stick theadditional substance to the metal-based structure, depending on thematerial or shape of the additional substance. On the other hand,according to the method described above, the metal-based structure isfirst formed, and then the composite structure is obtained by puttingthe additional substance in the cavity in the metal-based structure.Consequently, the chemical elements (elements concerning the reductionreaction) can be removed when the metal-based structure-additionalsubstance mixture is obtained. In addition, as described above, in themetal-based structure according to one embodiment of the presentinvention, the shape characteristic can be controlled with a goodrepeatability, and thus it is expected that the repeatability isexcellent in a stage in which the metal-based structure-additionalsubstance mixture is obtained by mixing the metal-based structure withthe additional substance.

In the composite structure produced in the method described above, aratio of a volume of the parts derived from the metal-based structure tothe whole volume of the composite structure is not particularly limited.The part derived from the metal-based structure may be main, or the partderived from the additional substance may be main. Specific examples ofthe case in which the component derived from the additional substance ismain may include the use of the metal-based structure as a sintering aidon the production of sintered parts such as a gear. As the metal-basedstructure according to one embodiment of the present invention containshydrogen, it is considered that the hydrogen has functions to remove anoxidized layer on the sintered material and to aid the diffusion of thesintered materials.

Another method for obtaining the composite structure may include amethod in which an additional substance is put in a cavity in thecrystallized metal-based structure. Specifically, a crystallizedmetal-based structure in a state in which cavities remain is immersed inliquid of a metal having a low melting point (for example, tin) to putthe metal in the cavity, and after that the crystallized metal-basedstructure is pulled up and cooled to room temperature, whereby acomposite structure formed of a crystallized metal-based structurehaving a cavities in which the metal having a low melting point is putcan be obtained.

8. Other Production Method

When the metal-based structure, the crystallized metal-based structure,or the composite structure, explained above, is subjected to at leastone treatment of the pressurization and the heating, the part structuresforming the structure, and the structure can be stuck to each other. Thestructure having excellent mechanical properties, which is obtained bydecreasing or substantially losing the volume of the cavities in thestructure, can be obtained by the sticking.

The specific method of the pressurization or the strength is notparticularly limited. There are cases in which a pressure is appliedmechanically, or a pressure is applied by increasing a magnetic fieldstrength to be applied. The heating temperature is not also limited. Inthe case of the metal-based structure, it may sometimes be preferable toadjust it to a crystallization temperature or higher. In the case of thecrystallized metal-based structure, it may sometimes be preferable toheat it until the cavities substantially disappear. In the case of thecomposite structure, it may sometimes preferable to heat it until theadditional substance is melted to fill the cavities with it.

In the specific one example of the metal-based structure as explainedabove, the structure containing Fe, as a main component, and inevitableimpurities is recited, as the component other than hydrogen. When themetal-based structure is produced by reduction of Fe ions in the liquid,as one example, there is a possibility of including the inevitableimpurity components contained in the reducing agent. The content of theinevitable impurity depends on parameter concerning the reductionreaction (an Fe ion concentration, a reducing agent concentration, atemperature, and the like). When the Fe ion concentration, the reducingagent concentration, and the solvent composition are adjusted toappropriate ranges, the content of the impurities is decreased, and ahigh purity metal-based structure formed of the single phase (αFe singlephase) of the main component can be produced. When the metal-basedstructure contains hydrogen, and has the amorphous part or is formed ofthe amorphous single phase, a high purity metal-based structure formedof the single phase of the main component (αFe single phase) maysometimes be obtained after the crystallization. In that case, it isconsidered that the metal-based structure containing the hydrogen, andhaving the amorphous part or being the amorphous single phase has thecomposition formed of Fe, which is the main component, and hydrogen.When the metal-based structure containing Fe as the main component isproduced in the method described above, if the concentration of thereducing agent is extremely small, the Fe element may exist in the oxidestate in the metal-based structure, because the reduction of Fe ion isinsufficient.

It is possible to produce the metal-based structure or the metal-basedstructure with a high purity whose composition is adjusted to apre-determined value by the production method described above. It isfurther possible to produce the metal material or composite metalmaterial formed of the desired alloy component by adding the additionalsubstance, or the like. The method is particularly preferable when thematerial formed of the nanosize particles or having the nanopartstructure is produced.

9. Application (Industrial Applicability)

The metal-based structure, crystallized metal-based structure, andcomposite structure according to the present invention are applicable tomagnetism materials, electrode materials, catalyst materials orstructure material utilizing a nanostructure; metal materials, structurematerials, and strength members utilizing the solidified substanceformed of nanostructure; a filter, holders for catalyst, and electrodemembers utilizing the nanosize mesh structure; and alloy and compositematerials utilizing the above. In addition, they are preferably utilizedas a shaped sintered body such as a screw or gear, or a materialthereof. They are also utilizable for a hydrogen occlusion body.

In the metal-based structure of the present invention, the formation ofthe oxide layer is suppressed, and thus the sticking formability ishigh, and it is very useful as a metal particle material for forming,coating materials, material for a 3D printer.

EXAMPLES

The present invention is explained in more detailed by means ofExamples, but the scope of the present invention is not limited toExamples.

The following findings about the present invention are obtained.

(A) The hydrogen-containing amorphous metal-based structure ispreferable for the formation of the nanostructure (the alignmentproperty of magnetic field, the adherence, and the formation of theformless phase).(B) The hydrogen content can be controlled by the combination of thesolutions and the solvent composition.(C) When the hydrogen content is high, the high purity metal-basedstructure can be obtained.(D) When the hydrogen content is high, the formless phase is formed.(E) The morphology can be selectively formed by applying the magneticfield to (A).

(A) to (E) are explained based on experimental results in Examplesbelow.

1. Example 1 1-1. Each Example Example 1-1 (1) Preparation of IronSulfate Solution

Aqueous iron sulfate solutions having a composition shown in Table 1were prepared as a part of liquid containing a reducible substance. Thesolution concentration (an iron sulfate content) was expressed as a molnumber of a solute per kg of a solvent (hereinafter the same, withrespect to the solution concentration). The bound water corresponding to7 hydrate, hydrate in iron (II) sulfate 7 hydrate, was added to thesolvent and concentrations were calculated.

TABLE 1 Kind of aqueous iron sulfate Iron(II)sulfate Water Ethanol Ironsulfate content Ethanol in solvent solution 7 hydrate[g] [g] [g][mmol/kg] Percentage[% by mass] FS1 0.30 13 3 67 19 FS2 0.30 13 3 67 19FS3 0.06 13 3 13 19 FS4 0.09 90 30 2.7 25 FS5 0.30 16 0 67 0 FS6 0.09120 0 2.7 0

(2) Preparation of Aqueous Reducing Agent Solution

As a reducing agent used for reducing an Fe ion (Fe²⁺) which was areducible component, aqueous reducing agent solutions containing NaBH₄and having a composition shown in Table 2 were prepared.

TABLE 2 Kind of aqueous NaBH4 NaBH4 Water Ethanol NaBH4 content Ethanolin solvent solution [g] [g] [g] [mmol/kg] Percentage [% by mass] NB10.20 15 0 350 0 NB2 0.06 25 0 63 0 NB3 0.04 15 0 70 0 NB4 0.06 45 15 2625 NB5 0.06 25 0 63 0 NB6 0.06 60 0 26 0

(3) Production of Metal-Based Structure

In a Schale (an outer diameter: 71 mm×a height: 16 mm, wall thickness: 2mm, made of glass, the Schale having the same shape was used in thefollowing Examples) was put 16 mL of an aqueous iron sulfate solution,prepared using iron (II) sulfate 7 hydrate (FeSO₄.7H₂O), manufactured byWako Pure Chemical Industries, Ltd. and indicated as FS1 in Table 1. Tothe liquid in the Schale was added dropwise, at 3 mL/minute, 15 mL of anaqueous reducing agent solution, prepared using sodium tetrahydroborate(NaBH₄) manufactured by Wako Pure Chemical Industries, Ltd. andindicated as NB1 in Table 2. The dropwise addition operation wasperformed from one nozzle while the addition position to the liquidsurface of the solution in the vessel (the Schale) was moved(hereinafter the same). The dropwise addition operation was performed atroom temperature (23° C.) (hereinafter the same). Other operations wereperformed at room temperature unless otherwise noted (hereinafter thesame). It was observed that bubbles and black murky deposit weregenerated around parts at which the aqueous reducing agent solution wasadded dropwise.

The water used in the aqueous iron sulfate solution and the aqueousreducing agent solution was distilled water, obtained using “GS-200 DIW”manufactured by ADVANTEC Co., Ltd. and classified into JISClassification A3 (JIS K 0577: 1998). Ethanol manufactured by KantoChemical Co., Inc. and having a GC purity of 99.5% or more was used.

The water and ethanol were used in washing works described below.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. After that,the liquid was filtered, and the filtered deposit was washed accordingto the following conditions:

i) A work in which 50 mL of distilled water was poured and casted wasperformed 3 times, and subsequentlyii) A work in which 50 mL of ethanol was poured and casted was performed3 times.

Hereinafter the washing condition above is referred to as “washingcondition 1.”

After the washing, the deposit was put in a beaker, which was dried in adesiccator to obtain a metal-based structure.

Example 1-2

In a Schale was put 16 mL of an aqueous iron sulfate solution indicatedas FS2 in Table 1. To the liquid in the Schale was added dropwise 25 mLof an aqueous reducing agent solution indicated as NB2 in Table 2 at 5mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes. Subsequently, aneodymium magnet-1 (an outer diameter: 15 mm×a thickness 6 mm, a surfaceinductive flux: 375 mT) was brought into contact with an outer bottomface of the Schale. It was observed that the deposit in the liquid movedtoward the magnet so as to approach the magnet. The liquid in the Schalewas allowed to stand for 5 minutes in the state in which the magnet wasbrought into contact with the bottom face of the Schale. The Schale wasslanted in the state in which the magnet was brought into contact withthe bottom face of the Schale to cast the liquid, whereby the depositremained inside the bottom face of the Schale.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the Schale.

After the washing, the magnet was separated from the bottom face of theSchale, and, while that state was maintained, the deposit remaining onthe bottom face of the Schale was recovered using a scoopula.

The recovered deposit was put in a glass tube (an outer diameter: 12 mm,an inner diameter: 10 mm, a length: 120 mm, made of Pyrex (registeredtrademark), hereinafter the same) whose one end was sealed, the insideof the glass tube was vacuum-dried at room temperature for 15 minutesusing a rotary pump without heating. An ultimate vacuum was 1.5 Pa.Hereinafter the vacuum-drying condition is referred to as “dryingcondition 1.”

While the exhaust ventilation in the glass tube was continued, the glasstube was heated from the outside with a heater to elevate thetemperature from room temperature (23° C.) to 400° C. (hereinafter, thehighest temperature reached by this heating may sometimes be referred toas the “heat temperature”). Specifically, the temperature was elevatedat 5° C./minute up to 100° C., and at 15° C./minute in a range of 100°C. or higher. The deposit was maintained at the heat temperature for 2minutes. The temperature was measured with a thermocouple, which was incontact with a tip of the glass tube. After that, while the exhaustventilation in the glass tube by the rotary pump was continued, thedeposit was allowed to cool until the measurement temperature reachedroom temperature. Hereinafter the heat-treatment condition is referredto as the “heat-treatment condition 1.” The exhaust ventilation in theglass tube by the rotary pump was finished to obtain a substance in theglass tube as a metal-based structure.

Example 1-3

In a Schale was put 16 mL of an aqueous iron sulfate solution indicatedas FS2 in Table 1. Subsequently, a ferrite magnet-1 (an outer diameter:17 mm×a thickness: 5 mm, a surface inductive flux: 85 mT) was broughtinto contact with an outer bottom face of the Schale. To the liquid inthe Schale was added dropwise 25 mL of an aqueous reducing agentsolution indicated as NB2 in Table 2 at 5 mL/minute. It was observedthat bubbles and black murky deposit were generated around parts in theliquid at which the aqueous reducing agent solution was added dropwise.It was also observed that the produced deposit moved toward the magnetin the liquid so as to approach the magnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of theSchale, and the Schale was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the Schale.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the Schale.

After the washing, the magnet was separated from the bottom face of theSchale, and, while the state was maintained, the deposit remaining onthe bottom face of the Schale was recovered using a scoopula.

The recovered deposit was put in a glass tube whose one end was sealed,which was dried in the drying condition 1. While the exhaust ventilationin the glass tube by using the rotary pump was continued, aheat-treatment was performed in the heat-treatment condition 1 in whichthe deposit was maintained at 400° C. for 2 minutes. The exhaustventilation in the glass tube by the rotary pump was finished to obtaina substance in the glass tube as a metal-based structure.

Example 1-4

In a Schale was put 16 mL of an aqueous iron sulfate solution indicatedas FS1 in Table 1. Subsequently, the ferrite magnet-1 (an outerdiameter: 15 mm) was brought into contact with an outer bottom face ofthe Schale. To the liquid in the Schale was added dropwise 15 mL of anaqueous reducing agent solution indicated as NB1 in Table 2 at 3mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of theSchale, and the Schale was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the Schale.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the Schale.

After the washing, the magnet was separated from the bottom face of theSchale, and, while the state was maintained, the deposit remaining onthe bottom face of the Schale was transferred to a beaker, which wasdried in a desiccator to obtain a metal-based structure.

Example 1-4-1

In a 200 mL beaker (made of Pyrex (registered trademark), an innerdiameter of the bottom: 63 mm, a thickness of the bottom: 1 to 2 mm,hereinafter the same) was put 48 mL of an aqueous iron sulfate solutionindicated as FS2 in Table 1. Subsequently, a neodymium magnet-2 (anouter diameter: 30 mm×a thickness: 30 mm, a surface inductive flux: 550mT) was brought into contact with an outer bottom face of the beaker. Tothe liquid in the beaker was added dropwise 75 mL of an aqueous reducingagent solution indicated as NB2 in Table 2 at 10 mL/minute. It wasobserved that bubbles and black murky deposit were generated aroundparts in the liquid at which the aqueous reducing agent solution wasadded dropwise. It was also observed that the deposit moved toward themagnet in the liquid so as to approach the magnet. After that, thedeposit was washed in the washing condition 1 in the same manner as inExample 1-4. After the washing, the magnet was separated from the bottomface of the beaker, and, while that state was maintained, the depositremaining on the bottom face of the beaker was recovered using ascoopula. The recovered deposit was put in a glass tube whose one endwas sealed, which was dried in the drying condition 1. While the exhaustventilation in the glass tube by using the rotary pump was continued, aheat-treatment was performed according to the heat-treatment condition 1in which the deposit was maintained at 150° C. for 2 minutes. Theexhaust ventilation in the glass tube by the rotary pump was finished toobtain a substance in the glass tube as a metal-based structure.

Example 1-4-2

In a 100 mL beaker (made of Pyrex (registered trademark), an innerdiameter of the bottom: 51 mm, a thickness of the bottom: 1 to 2 mm,hereinafter the same) was put 16 mL of an aqueous iron sulfate solutionindicated as FS2 in Table 1. Subsequently, a neodymium magnet-1 (anouter diameter: 15 mm) was set on an inside bottom face of the beaker.To the liquid in the beaker was added dropwise 25 mL of an aqueousreducing agent solution indicated as NB2 in Table 2 at 5 mL/minute. Itwas observed that bubbles and black murky deposit were generated aroundparts in the liquid at which the aqueous reducing agent solution wasadded dropwise. It was also observed that the deposit moved toward themagnet in the liquid so as to approach the magnet. After that, thedeposit was washed in the washing condition 1, was dried in the dryingcondition 1, and consequently was subjected to a heat-treatment in theheat-treatment condition 1 in which the deposit was maintained at 150°C. for 2 minutes, in the same manner as in Example 1-4-1, whereby ametal-based structure was obtained.

Example 1-4-3

The same procedures as in Example 1-4 were performed up to the washingcondition 1. After that, the recovered deposit was put in a glass tubewhose one end was sealed, was dried in the drying condition 1, and,continuously, was subjected to a heat-treatment in the heat-treatmentcondition 1 in which the deposit was maintained at 400° C. for 2minutes, whereby a metal-based structure was obtained.

Example 1-4-4

A metal-based structure, obtained in the same procedures as in Example1-4-1, was subjected to a heat-treatment in the heat-treatment condition1 and, subsequently, while the exhaust ventilation in the glass tube bythe rotary pump was continued, a glass tube is vacuum-sealed in thestate in which the substance was put in the glass tube. Thevacuum-sealing operation was an operation in which, while the exhaustventilation in the glass tube was continued, the glass tube was heatedfrom the outside with a gas burner at a position sufficiently distant sothat the substance in the glass tube was not affected by the heat toreduce the diameter of the glass tube, whereby the substance wasvacuum-sealed, and the glass tube was cut. After the vacuum-sealing, theglass tube had a length of about 70 mm. Hereinafter, the vacuum-sealingwas performed in the same manner as above. The resulting glass tube wasmaintained at 500° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

Example 1-5

In a Schale was put 16 mL of an aqueous iron sulfate solution indicatedas FS3 in Table 1. Subsequently, a ferrite magnet-1 (an outer diameter:17 mm) was brought into contact with an outer bottom face of the Schale.To the liquid in the Schale was added dropwise 15 mL of an aqueousreducing agent solution indicated as NB3 in Table 2 at 3 mL/minute. Itwas observed that bubbles and black murky deposit were generated aroundparts in the liquid at which the aqueous reducing agent solution wasadded dropwise. It was also observed that the produced deposit movedtoward the magnet in the liquid so as to approach the magnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of theSchale, and the Schale was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the Schale.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the Schale.

After the washing, the magnet was separated from the bottom face of theSchale, and, while the state was maintained, the deposit remaining onthe bottom face of the Schale was recovered using a scoopula.

The recovered deposit was put in a glass tube whose one end was sealed,and was dried in the drying condition 1. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 200° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

Example 1-6

In a Schale was put 16 mL of an aqueous iron sulfate solution indicatedas FS3 in Table 1. Subsequently, a neodymium magnet-1 (an outerdiameter: 15 mm) was brought into contact with an outer bottom face ofthe Schale. To the liquid in the Schale was added dropwise 15 mL of anaqueous reducing agent solution indicated as NB3 in Table 2 at 3mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of theSchale, and the Schale was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the Schale.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the Schale.

After the washing, the magnet was separated from the bottom face of theSchale, and, while the state was maintained, the deposit remaining onthe bottom face of the Schale was recovered using a scoopula.

The recovered deposit was put in a glass tube whose one end was sealed,and was dried in the drying condition 1. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 400° C. for 15 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

Example 1-7

In a 200 mL beaker was put 120 mL of an aqueous iron sulfate solutionindicated as FS4 in Table 1. To the liquid in the beaker was addeddropwise 60 mL of an aqueous reducing agent solution indicated as NB4 inTable 2 at 10 mL/minute. It was observed that bubbles and black murkydeposit were generated around parts in the liquid at which the aqueousreducing agent solution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. Subsequently,a neodymium magnet-1 (an outer diameter: 15 mm) was brought into contactwith an outer bottom face of the beaker. It was observed that thedeposit moved toward the magnet in the liquid so as to approach themagnet. The liquid in the schale was allowed to stand for 5 minutes inthe state in which the magnet was brought into contact with the bottomface of the beaker. The beaker was slanted in the state in which themagnet was brought into contact with the bottom face of the beaker tocast the liquid, whereby the deposit remained inside the bottom face ofthe beaker.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the beaker.

After the washing, the magnet was separated from the bottom of thebeaker, and, while the state was maintained, the deposit remaining onthe bottom face of the beaker was recovered using a scoopula.

The work described above was performed twice in total, the recovereddeposit was put in a glass tube whose one end was sealed, and was driedin the drying condition 1. While the exhaust ventilation in the glasstube by the rotary pump was continued, the heat-treatment was performedin the heat-treatment condition 1 in which the deposit was maintained at200° C. for 2 minutes. The exhaust ventilation in the glass tube by therotary pump was finished, and the substance in the glass tube wasobtained as a metal-based structure.

Example 1-7-1

The same procedures as in Example 1-7 were performed up to the drying inthe drying condition 1. While the exhaust ventilation in the glass tubeby the rotary pump was continued, the heat-treatment was performed inthe heat-treatment condition 1 in which the deposit was maintained at50° C. for 2 minutes. The exhaust ventilation in the glass tube by therotary pump was finished, and the substance in the glass tube wasobtained as a metal-based structure.

Example 1-7-2

In a 1 L beaker was put 480 mL of an aqueous iron sulfate solutionindicated as FS4 in Table 1. To the liquid in the beaker was addeddropwise 240 mL of an aqueous reducing agent solution indicated as NB4in Table 2 at 25 mL/minute. It was observed that bubbles and black murkydeposit were generated around parts in the liquid at which the aqueousreducing agent solution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. Subsequently,a part of the liquid in the 1 L beaker was transferred to a 200 mLbeaker with which a neodymium magnet-2 (an outer diameter: 30 mm) wasbrought into contact on the outer bottom face thereof. It was observedthat the deposit moved toward the magnet in the liquid so as to approachthe magnet. The liquid in the beaker was allowed to stand for 5 minutesin the state in which the magnet was brought into contact with thebottom face of the beaker. The beaker was slanted in the state in whichthe magnet was brought into contact with the bottom face of the beakerto cast the liquid, whereby the deposit remained inside the bottom faceof the beaker. While the magnet was brought into contact with thebeaker, the work was performed 5 times in total. After the washing wasperformed in the washing condition 1, the magnet was separated from thebottom face of the beaker, and the deposit in the 1 L beaker wasrecovered.

The work described above was performed twice in total, and the obtaineddeposit was put in a glass tube whose one end was sealed and dried inthe drying condition 1. While the exhaust ventilation in the glass tubeby the rotary pump was continued, the heat-treatment was performed inthe heat-treatment condition 1 in which the deposit was maintained at200° C. for 2 minutes. The exhaust ventilation in the glass tube by therotary pump was finished, and the substance in the glass tube wasobtained as a metal-based structure.

Example 1-7-3

The same procedure as in Example 1-7 were performed up to the drying inthe drying condition 1. While the exhaust ventilation in the glass tubeby the rotary pump was continued, the heat-treatment was performed inthe heat-treatment condition 1 in which the deposit was maintained at300° C. for 2 minutes. The exhaust ventilation in the glass tube by therotary pump was finished, and the substance in the glass tube wasobtained as a metal-based structure.

Example 1-7-4

The same procedures as in Example 1-7 was performed up to the drying inthe drying condition 1. While the exhaust ventilation in the glass tubeby the rotary pump was continued, the heat-treatment was performed inthe heat-treatment condition 1 in which the deposit was maintained at400° C. for 30 minutes. After the heat-treatment, the substance in theglass tube was obtained as a metal-based structure.

Example 1-7-5

The same procedures as in Example 1-7-2 were performed up to theoperation in the washing condition 1 except that the amount of theaqueous iron sulfate solution used was 240 mL, the amount of the aqueousreducing agent solution used was 120 mL, and the dropwise addition ratewas 20 mL/minute. The obtained deposit was put in a glass tube whose oneend was sealed, and was dried in the drying condition 1. While theexhaust ventilation in the glass tube by the rotary pump was continued,the heat-treatment was performed in the heat-treatment condition 1 inwhich the deposit was maintained at 150° C. for 2 minutes. After that,while the exhaust ventilation was continued, the glass tube wasvacuum-sealed in a state in which the substance was put in the glasstube. The glass tube was maintained at 600° C. for 60 minutes using anair atmosphere furnace with a temperature elevation rate of 20°C./minute, and was cooled to room temperature in the furnace, wherebythe substance in the glass tube after the heat-treatment was obtained asa metal-based structure.

Example 1-8

A ferrite magnet-1 (an outer diameter: 17 mm) was brought into contactwith an outer bottom face of a 100 mL beaker. In the beaker was put 20mL of an aqueous iron sulfate solution indicated as FS4 in Table 1.Subsequently, to the liquid in the beaker was added dropwise 10 mL of anaqueous reducing agent solution indicated as NB4 in Table 2 at 3mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, and the beaker was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the beaker. In the beaker was put 20 mL of an aqueous ironsulfate solution in the state in which the magnet was brought intocontact with the bottom face of the beaker, the dropwise additionoperation described above was repeated again, and the deposit was washedin the washing condition 1.

After the washing, the magnet was separated from the bottom of thebeaker, and, while the state was maintained, the deposit remaining onthe bottom face of the beaker was recovered using a scoopula.

The work above was repeated twice, and the work was performed 4 times intotal. The obtained deposit was put in a glass tube whose one end wassealed, and was dried in the drying condition 1. While exhaustventilation in the glass tube by the rotary pump was continued, theheat-treatment was performed in the heat-treatment condition 1 in whichthe deposit was maintained at 150° C. for 2 minutes. The exhaustventilation in the glass tube by the rotary pump was finished, and thesubstance in the glass tube was obtained as a metal-based structure.

Example 1-9

The same dropwise addition operation as in Example 1-8 was performedexcept that the magnet, which was brought into contact with the beaker,was a neodymium magnet-1 (an outer diameter: 15 mm). After the dropwiseaddition of the aqueous reducing agent solution was finished, the liquidwas allowed to stand for 5 minutes in the state in which the magnet wasbrought into contact with the bottom face of the beaker, and the beakerwas slanted while the state was maintained to cast the liquid. As aresult, the deposit remained inside the bottom face of the beaker.

The dropwise addition operation was repeated 5 times in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, and the deposit was washed in the washing condition 1.

After the washing, the magnet was separated from the bottom of thebeaker, and, while the state was maintained, the deposit remaining onthe bottom face of the beaker was recovered using a scoopula.

The deposit, obtained in the above work, was put in a glass tube whoseone end was sealed, and was dried in the drying condition 1. While theexhaust ventilation in the glass tube by the rotary pump was continued,the heat-treatment was performed in the heat-treatment condition 1 inwhich the deposit was maintained at 250° C. for 2 minutes. The exhaustventilation in the glass tube by the rotary pump was finished, and thesubstance in the glass tube was obtained as a metal-based structure.

Example 1-9-1

A part of the metal-based structure obtained in Example 1-9 was put in aglass tube whose one side was sealed, and was dried in the dryingcondition 1. While the exhaust ventilation in the glass tube by therotary pump was continued, the glass tube was vacuum-sealed in a statein which the substance was put in the glass tube. The glass tube wasmaintained at 600° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

Example 1-9-2

A part of the metal-based structure obtained in Example 1-9 was put in aglass tube whose one side was sealed, and was dried in the dryingcondition 1. While the exhaust ventilation in the glass tube by therotary pump was continued, glass tube was vacuum-sealed in a state inwhich the substance was put in the glass tube. The glass tube wasmaintained at 800° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

(Example 1-9-3) XRD Measurement

A neodymium magnet-2 (an outer diameter: 30 mm) was brought into contactwith an outer bottom face of a 500 mL beaker. In the beaker was put 240mL of an aqueous iron sulfate solution indicated as FS4 in Table 1.Subsequently, to the liquid in the beaker was added dropwise 120 mL ofan aqueous reducing agent solution indicated as NB4 in Table 2 at 20mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, the beaker was slanted while the state was maintained to castthe liquid. As a result, the deposit remained inside the bottom face ofthe beaker. The deposit was washed in the washing condition 1 in thestate in which the magnet was brought into contact with the bottom faceof the beaker.

After the washing, the magnet was separated from the bottom of thebeaker, and, while the state was maintained, the deposit remaining onthe bottom face of the beaker was recovered using a scoopula.

The deposit, obtained in the work as above, was put in a glass tubewhose one end was sealed, and was dried in the drying condition 1. Whilethe exhaust ventilation in the glass tube by the rotary pump wascontinued, the heat-treatment was performed in the heat-treatmentcondition 1 in which the deposit was maintained at 150° C. for 2minutes. After that, while the exhaust ventilation in the glass tube wascontinued, the glass tube was vacuum-sealed in a state in which thesubstance was put in the glass tube. After the glass tube was maintainedat 600° C. for 60 minutes using an air atmosphere furnace with atemperature elevation rate of 20° C./minute, the heating was stopped,and the glass tube was cooled to room temperature in the furnace. Afterthe heat-treatment, the substance in the glass tube was obtained as ametal-based structure, which was subjected to an XRD measurement (FIG.63).

Example 1-10

In a 200 mL beaker was put 48 mL of an aqueous iron sulfate solutionindicated as FS5 in Table 1. To the liquid in the beaker was addeddropwise 75 Lm of an aqueous reducing agent solution indicated as NB5 inTable 2 at 10 mL/minute. It was observed that bubbles and black murkydeposit were generated around parts in the liquid at which the aqueousreducing agent solution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. After it wasallowed to stand, the liquid was filtered, the filtered deposit waswashed in the washing condition 1.

After the washing, the deposit remaining on the bottom face of thebeaker was recovered using a scoopula.

The washed deposit was put in a glass tube whose one side was sealed,and was dried in the drying condition 1. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 150° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

Example 1-10-1

A part of the metal-based structure obtained in Example 1-10 was put ina glass tube whose one side was sealed, and was dried in the dryingcondition 1. While the exhaust ventilation in the glass tube by therotary pump was continued, the glass tube was vacuum-sealed in a statein which the substance was put in the glass tube. The glass tube wasmaintained at 600° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

(Example 1-11) XRD Measurement (the Phase is Called “X1 Phase.”)

In a 100 mL beaker was put 16 mL of an aqueous iron sulfate solutionindicated as FS5 in Table 1. Subsequently, a neodymium magnet-2 (anouter diameter: 30 mm) was brought into contact with an outer bottomface of the beaker. To the liquid in the beaker was added dropwise 25 mLof an aqueous reducing agent solution indicated as NB5 in Table 2 at 5mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, and the beaker was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the beaker.

The deposit was washed in the washing condition 1 in the state in whichthe magnet was brought into contact with the bottom face of the beaker.

The washed deposit was put in a glass tube whose one side was sealed,and was dried in the drying condition 1. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 150° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure. The resultingmetal-based structure was subjected to an XRD measurement (FIG. 47).

Example 1-11-1

The same procedures as in Example 1-11 was performed up to the drying inthe drying condition 1. While the exhaust ventilation in the glass tubeby the rotary pump was continued, the heat-treatment was performed inthe heat-treatment condition 1 in which the deposit was maintained at150° C. for 2 minutes. After that, the glass tube was vacuum-sealed in astate in which the substance was put in the glass tube. The glass tubewas maintained at 400° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

Example 1-11-2

The same procedures as in Example 1-11 were performed up to the dryingin the drying condition 1 except that the amount of the aqueous ironsulfate solution used was 48 mL, the amount of the aqueous reducingagent solution used was 75 mL, the dropwise addition rate was 10mL/minute, and a 200 mL beaker was used. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 200° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

(Example 1-11-3) Measurement of Hydrogen Content and SEM Measurement

The same procedures as in Example 1-11 were performed up to the dryingin the drying condition 1 except that the amount of the aqueous ironsulfate solution used was 48 mL, the amount of the aqueous reducingagent solution used was 75 mL, the dropwise addition rate was 10mL/minute, and a 200 mL beaker was used. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 450° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

(Example 1-11-4) XRD Measurement (the Phase is Called X2 Phase.)

A part, 30 mg, of the metal-based structure in Example 1-11-3 wassubjected to an XRD measurement (FIG. 64).

(Example 1-11-5) XRD Measurement (the Phase is Called X3 Phase.)

After the XRD measurement of the metal-based structure was performed inExample 1-11-4, nearly the entire amount thereof was put in a glass tubewhose one side was sealed, and was dried in the drying condition 1.While the exhaust ventilation in the glass tube by the rotary pump wascontinued, the heat-treatment was performed in the heat-treatmentcondition 1 in which the deposit was maintained at 150° C. for 2minutes. While the exhaust ventilation was further continued, the glasstube was vacuum-sealed in a state in which the substance was put in theglass tube. The glass tube was maintained at 600° C. for 60 minutesusing an air atmosphere furnace with a temperature elevation rate of 20°C./minute, and was cooled to room temperature in the furnace. After theheat-treatment, the substance in the glass tube was obtained as ametal-based structure, and nearly the entire amount thereof wassubjected to an XRD measurement (FIG. 65).

Example 1-12

In a 200 mL beaker was put 120 mL of an aqueous iron sulfate solutionindicated as FS6 in Table 1. To the liquid in the beaker was addeddropwise 60 mL of an aqueous reducing agent solution indicated as NB6 inTable 2 at 10 mL/minute. It was observed that bubbles and black murkydeposit were generated around parts in the liquid at which the aqueousreducing agent solution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. Subsequently,a neodymium magnet-2 (an outer diameter: 30 mm) was brought into contactwith an outer bottom face of the beaker. It was observed that thedeposit moved toward the magnet in the liquid so as to approach themagnet. The liquid in the beaker was allowed to stand for 5 minutes inthe state in which the magnet was brought into contact with the bottomface of the beaker. The beaker was slanted in the state in which themagnet was brought into contact with the bottom face of the beaker tocast the liquid, whereby the deposit remained inside the bottom face ofthe beaker.

After the deposit was washed in the washing condition 1 in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, the deposit was recovered.

The work described above was performed twice in total, the obtaineddeposit was put in a glass tube whose one end was sealed, and was driedin the drying condition 1. While the exhaust ventilation in the glasstube by the rotary pump was continued, the heat-treatment was performedin the heat-treatment condition 1 in which the deposit was maintained at150° C. for 2 minutes. The exhaust ventilation in the glass tube by therotary pump was finished, and the substance in the glass tube wasobtained as a metal-based structure.

Example 1-12-1

In a 1 L beaker was put 480 mL of an aqueous iron sulfate solutionindicated as FS6 in Table 1. To the liquid in the beaker was addeddropwise 240 mL of an aqueous reducing agent solution indicated as NB6in Table 2 at 25 mL/minute. It was observed that bubbles and black murkydeposit were generated around parts in the liquid at which the aqueousreducing agent solution was added dropwise.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes. Subsequently,a part of the liquid in the 1 L beaker was transferred to a 200 mLbeaker with which a neodymium magnet-2 (an outer diameter: 30 mm) wasbrought into contact on the outer bottom face thereof. It was observedthat the deposit moved toward the magnet in the liquid so as to approachthe magnet. The liquid in the beaker was allowed to stand for 5 minutesin the state in which the magnet was brought into contact with thebottom face of the beaker. The beaker was slanted in the state in whichthe magnet was brought into contact with the bottom face of the beakerto cast the liquid, whereby the deposit remained inside the bottom faceof the beaker. While the magnet was brought into contact with thebeaker, the work was performed 5 times in total, and the washing wasperformed in the washing condition 1. After that, the magnet wasseparated from the bottom face of the beaker, and the deposit in the 1 Lbeaker was recovered.

The work described above was performed twice in total, the depositobtained in the work above was put in a glass tube whose one side wassealed, and was dried in the drying condition 1. While the exhaustventilation in the glass tube by the rotary pump was continued, theheat-treatment was performed in the heat-treatment condition 1 in whichthe deposit was maintained at 200° C. for 2 minutes. The exhaustventilation in the glass tube by the rotary pump was finished, and thesubstance in the glass tube was obtained as a metal-based structure.

Example 1-12-2

A part of the metal-based structure obtained in Example 1-12 was put ina glass tube whose one side was sealed, and was dried in the dryingcondition 1. While the exhaust ventilation in the glass tube by therotary pump was continued, glass tube was vacuum-sealed in a state inwhich the substance was put in the glass tube. The glass tube wasmaintained at 600° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure.

Example 1-13

In a 200 mL beaker with which a neodymium magnet-2 (an outer diameter:30 mm) was brought into contact on an outer bottom face of the beakerwas put 60 mL of an aqueous iron sulfate solution indicated as FS6 inTable 1. To the liquid in the beaker was added dropwise 30 mL of anaqueous reducing agent solution indicated as NB6 in Table 2 at 10mL/minute. It was observed that bubbles and black murky deposit weregenerated around parts in the liquid at which the aqueous reducing agentsolution was added dropwise. It was also observed that the produceddeposit moved toward the magnet in the liquid so as to approach themagnet.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 5 minutes in the state inwhich the magnet was brought into contact with the bottom face of thebeaker, and the beaker was slanted while the state was maintained tocast the liquid. As a result, the deposit remained inside the bottomface of the beaker.

After the dropwise addition work described above was performed 4 timesin total in the state in which the magnet was brought into contact withthe bottom face of the beaker, the deposit was washed in the washingcondition 1.

The obtained deposit was put in a glass tube whose one end was sealed,and was dried in the drying condition 1. While the exhaust ventilationin the glass tube by the rotary pump was continued, the heat-treatmentwas performed in the heat-treatment condition 1 in which the deposit wasmaintained at 150° C. for 2 minutes. The exhaust ventilation in theglass tube by the rotary pump was finished, and the substance in theglass tube was obtained as a metal-based structure.

Example 1-13-1

The metal-based structure, obtained in the same manner as in Example1-13, was put in a glass tube whose one side was sealed, and was driedin the drying condition 1. While the exhaust ventilation in the glasstube by the rotary pump was continued, the glass tube was vacuum-sealedin a state in which the substance was put in the glass tube. Thevacuum-sealed glass tube was maintained at 600° C. for 60 minutes usingan air atmosphere furnace with a temperature elevation rate of 20°C./minute, and was cooled to room temperature in the furnace. After theheat-treatment, the substance in the glass tube was obtained as ametal-based structure.

(Example 1-14) XRD Measurement (the Phase is Called Y1 Phase.)

In a 200 mL beaker was put 48 mL of an aqueous iron sulfate solutionindicated as FS5 in Table 1. Subsequently, 75 mL of an aqueous reducingagent solution indicated as NB5 in Table 2 was poured into the liquid inthe beaker in 20 seconds (about 4 mL/second). It was confirmed toproduce black murky deposit in the liquid in which bubbles were ratherviolently generated, and it was observed that the stirring wassufficiently performed by the generation of the bubbles during thepouring of the aqueous reducing agent solution. After the pouring wasfinished, subsequently the stirring was performed for 10 minutes with aglass rod. The obtained deposit was extracted through a filter paper,and washed in the washing condition 1. After that, a half amount thereofwas dried in a desiccator having a temperature of room temperature toobtain a metal-based structure, which was subjected to an XRDmeasurement (FIG. 66).

(Example 1-14-1) Measurement of Hydrogen Content

After the same procedures as in Example 1-14 was performed up to thewashing of the deposit in washing condition 1, it was put in a glasstube whose one side was sealed, and was dried in the drying condition 1.While the exhaust ventilation in the glass tube by the rotary pump wascontinued, the heat-treatment was performed in the heat-treatmentcondition 1 in which the deposit was maintained at 200° C. for 2minutes. The exhaust ventilation in the glass tube by the rotary pumpwas finished, and the substance in the glass tube was obtained as ametal-based structure.

(Example 1-14-2) XRD Measurement (the Phase is Called Y3 Phase.)

After the washing was performed in the washing condition 1 in Example1-14, the half of the remaining was put in a glass tube whose one sidewas sealed, and was dried in the drying condition 1. While the exhaustventilation in the glass tube by the rotary pump was continued, theheat-treatment was performed in the heat-treatment condition 1 in whichthe deposit was maintained at 150° C. for 2 minutes. While the exhaustventilation was further continued, the glass tube was vacuum-sealed in astate in which the substance was put in the glass tube. The glass tubewas maintained at 600° C. for 60 minutes using an air atmosphere furnacewith a temperature elevation rate of 20° C./minute, and was cooled toroom temperature in the furnace. After the heat-treatment, the substancein the glass tube was obtained as a metal-based structure, which wassubjected to an XRD measurement (FIG. 67).

1-2. Measurement (Measurement 1) X-Ray Diffraction

Using an X-ray diffraction apparatus (“NEW D8 ADVANCE” manufactured byBRUKER AXS Corporation), diffraction spectrum measurements of themetal-based structures obtained in Examples according to X-ray (Cu-Kαray) were performed.

Measurement results are shown in FIG. 39 to FIG. 52.

The relationships in each Example, Fig. and measurement results are asfollows:

Example 1-1 FIG. 39 amorphous single phase Example 1-4 FIG. 40 amorphoussingle phase Example 1-4-4 FIG. 41 αFe single phase Example 1-7 FIG. 42amorphous single phase Example 1-7-5 FIG. 43 αFe single phase Example1-9 FIG. 44 amorphous single phase Example 1-9-3 FIG. 63 αFe singlephase Example 1-10 FIG. 45 a phase containing mainly amorphous substanceExample 1-10-1 FIG. 46 αFe single phase Example 1-11 FIG. 47 amorphoussingle phase Example 1-11-1 FIG. 48 αFe phase Example 1-11-4 FIG. 64 αFephase Example 1-11-5 FIG. 65 αFe single phase Example 1-12 FIG. 49amorphous single phase Example 1-12-2 FIG. 50 Fe₂B single phase Example1-13 FIG. 51 amorphous single phase Example 1-13-1 FIG. 52 Fe₂B and αFeare mixed Example 1-14 FIG. 66 αFe phase Example 1-14-2 FIG. 67 αFesingle phase

In the obtained diffraction spectrum, when only a peak substantiallybased on the αFe was observed, it was judged that the metal-basedstructure imparting the diffraction spectrum was an αFe single phase.

From the result, the following items can be understood.

(A) It was confirmed to obtain, in the production method according tothe present invention, the metal-based structure mainly containing theamorphous single phase or the amorphous.(B) It was confirmed to obtain the crystallized metal-based structure ofthe metal single phase, which was formed of the metal αFe single phase,the intermetallic compound Fe₂B single phase, or a mixed phase thereof,by subjecting the metal-based structure mainly containing the amorphoussingle phase or the amorphous part to the heating operation.

A judgment about whether or not the crystal phase can be formed is shownin X1 phase/X2 phase/X3 phase in Examples, and is judged as follows:

(a) In the XRD measurement results (FIG. 47_X1), when an amorphoussubstance which is judged to be an amorphous single phase containing nocrystal phase (which is called X1 phase) was subjected to, for example,a heat-treatment at 450° C., a peak considered to be a crystal phase(which is called X2 phase) appears in the XRD measurement results (FIG.64_X2).(b) In the XRD measurement results (FIG. 65_X3), when the metal-basedstructure containing the crystal phase shown in FIG. 64_X2 (X2 phase) issubjected to, for example, a heat-treatment at 600° C., a crystal phasehaving higher crystallinity as shown in FIG. 65_X3 (which is called X3phase) can be obtained.

In the case (a) in which there is a phase change of X1 phase to X2 phaseor the case (b) in which there is a phase change of X2 phase to X3phase, when it is judged that the crystallinity is relatively increasedin each of (a) and (b), i.e., regions of the ordered structure areincreased, in the XRD measurement results, it is assessed that thecrystal phase is formed from the amorphous phase in the amorphous part.It is preferable to perform measurements in the same conditions asabove, and to relatively assess them.

The judgements are made as described below based on the judgement methodabove from experimental results.

-   -   X1 phase has an amorphous part capable of forming a crystal        phase (the number of XRD peaks is increased), from the results        of X2 phase.    -   X2 phase has an amorphous part capable of forming a crystal        phase (the XRD peak is changed from broad to sharp peak, and a        ratio of a peak intensity is increased) from the results of X3        phase. It is desirable that the assessment in which the        crystallinity is increased or the ordered structure range is        increased is performed by an intercomparison. For example, the        judgement is made by increase of a regularity of an atomic        arrangement relatively comparing the XRD measurement results        obtained in the same conditions. In addition, the judgement may        sometimes be made by existence of at least one of        characteristics described below.        (α) The number of peaks is increased.        (β) A half-value width (HW [°]), which is an angle width at a        half value of the peak intensity, is narrowed. The peak is        changed from broad to sharp peak.        (γ) A ratio of an intensity of a peak intensity to a noise        intensity width of a base having no peak is increased.    -   Intensity of peak is referred to as an intensity difference        between the maximum value of a peak intensity and an        extrapolation value of a base containing no peak (an average        value, considering noises).

From the XRD measurement results in Example 1-11-4 (FIG. 64), Example1-11-5 (FIG. 65), Example 1-14 (FIG. 66), and Example 1-14-2 (FIG. 67),the half-value widths (HW [°]), obtained based on the maximum peak, wererespectively 0.78, 0.18, 0.85, and 0.19, and the intensity ratios of thepeak (Ip/N) were respectively 20, 102, 23, and 153. When there weredifferences in the half-value width and the intensity ratio being twiceor more, the half-value width was decreased and/or the intensity ratiowas increased. From the results, it is assessed that the regularity ofthe amorphous part is relatively increased and the crystallization isadvanced.

(Measurement 2) Measurement of Hydrogen Content

The content of hydrogen contained in the metal-based structure wasmeasured. The hydrogen content was calculated by dividing a mass ofhydrogen, obtained by a measurement described below, by an amount of asample weighed, and multiplying the obtained value by 100, and expressedas a hydrogen content in the sample [% (mass percentage)], which ishereinafter referred to as % by mass.

The measurement method was in accordance with JIS Z 2614 “General Rulesfor Determination of Hydrogen in Metallic Materials.” The measurementwas performed using an apparatus described in JIS H 1619 “Titanium andTitanium Alloys-Determination of Hydrogen Content.” Specifically,measurement was performed with hydrogen as it is, JIS H 1619 Titaniumand Titanium Alloys-Determination of Hydrogen Content 5 Inert GasMelted-Thermal Conductivity Method.

A sample was heat-melted together with tin using a graphite crucible inan inert gas stream in an impulse furnace, and hydrogen was extractedwith other gases. The extracted gases were passed through a separationcolumn as they were to separate hydrogen from them, and the hydrogen wasintroduced into a thermal conductivity detector, thereby measuring achange of a thermal conductivity caused by hydrogen.

Other conditions were as follows:

Sample state: PowderPreparation method of sample: After heat-drying at 105° C. in a 2 Hratmosphere, cooling to room temperature was performed in a desiccator,and mixing was performed to uniformize.Collection method of sample: A powdery sample was weighed at a g (gram)unit up to the fourth decimal place,Quantitative method(Gas extraction method): Inert gas fusion method(Gas analysis method): Thermal conductivity methodGas extraction temperature (a temperature at which an analysis sample isfused and gas is released): 2000° C.Gas collection time: 75 secondsBlank test value: 0.000003% (0.03 ppm)Measurement apparatus: EMGA 621A-type manufactured by HORIBA Ltd.Amount of sample weighed and control method thereof

About 100 mg of a powdery sample was subjected to an analysis in eachcondition.

Degassing temperature (=a blank baking temperature of a crucible): A, B,and C were performed in this order.A: 3200° C.-30 secondsB: 2100° C.-15 secondsC: 2000° C.-5 secondsKind and purity of inert gas used in extraction: Ar, 99.999%Denitrogenation and deoxygenation agent of inert gas, and dehydratingagent:No denitrogenation and deoxygenation agentMagnesium perchlorate was used as the dehydrating agent.

As a result of the measurements above, the hydrogen contents were 0.22%by mass for the metal-based structure obtained in Example 1-7-2; 0.10%by mass for the metal-based structure obtained in Example 1-11-2; and0.02% by mass for the metal-based structure obtained in Example 1-12-1.From the results of Examples 1-7-5 and 1-11-5, it can be considered thata parent phase is Fe. At that time, hydrogen contents as an atomicfraction (a hydrogen content [% (atomic fraction)] in the sample,hereinafter expressed as % by atom) of the metal-based structureobtained in Example 1-7-2 and the metal-based structure obtained inExample 1-11-2 are respectively converted as 11.0% by atom and 5.3% byatom. With respect to Example 1-12-1, it can be considered that a parentphase may be a phase formed of Fe₂B or a phase having the samecomposition ratio of Fe₂B, from the results in Example 1-12-2, and thehydrogen content was converted as 0.81% by atom.

As a result of the measurement, a hydrogen content of the metal-basedstructure obtained in Example 1-11-3 was 0.06% by mass. From the resultsin Example 1-11-5, it can be considered that a parent phase is Fe, andthe hydrogen content as an atomic fraction of the metal-based structurewas converted as 3.2% by atom.

Further as a result of the measurement, a hydrogen content of themetal-based structure obtained in Example 1-14-1 was 0.06% by mass. Fromthe results in Example 1-14-2, it can be considered that a parent phaseis Fe, and the hydrogen content as an atomic fraction of the metal-basedstructure was converted as 3.2% by atom. Table in which the results aresummarized is shown below.

TABLE 3 Hydrogen Hydrogen content content Example (% by mass) (% byatom) Parent Phase 1-7-2 0.22 11.0 Fe amorphous single phase 1-11-2 0.105.3 Fe amorphous single phase 1-11-3 0.06 3.2 Fe amorphous substance +αFe crystal phase 1-12-1 0.02 0.81 Fe₂B amorphous single phase 1-14-10.06 3.2 Fe amorphous substance + αFe crystal phase

From the results, it was confirmed that the metal-based structureaccording to the present invention was the hydrogen-containingmetal-based structure, and further was the hydrogen-containing amorphousstructure.

As described above, the hydrogen, which does not go out from themetal-based structure when the metal-based structure of the presentinvention is heated at 200° C. for 2 minutes, is the non-diffusiblehydrogen. It can be said accordingly that the hydrogen content describedabove is the content of the non-diffusible hydrogen, because it is thehydrogen content after the structure is heated at 200° C. for 2 minutes.

As described above, when hydrogen is contained in the metal-basedstructure, the crystallization of the metal-based reduced substance isinhibited when it is grown, as a result, it can be said that theamorphous state or a state close thereto is generated in the metal-basedstructure. It is accordingly assumed that when hydrogen was contained,the amorphous phase was formed.

When this is seen from the aspect of the hydrogen content, it can besaid that the formation of the amorphous phase could be controlled bycontrolling the hydrogen content of the metal-based structure.

(Mixing Step by Dropwise Addition and Mixing Step by Stirring)

There are differences described below between the mixing step by thedropwise addition and the mixing step by stirring. When the mixing bythe dropwise addition was performed, the metal-based structure after thedeposition was the amorphous single phase (Example 1-11, FIG. 47, X1phase) and the hydrogen content was 0.1% by weight (Example 1-11-2).After the heat-treatment at 600° C., the structure was the αFe singlephase, and only the existence of the Fe element was observed (Example1-11-5, X3 phase). On the other hand, when the mixing by stirring wasperformed, the metal-based structure after the deposition was the αFephase (Example 1-14, FIG. 66, Y1 phase) and the hydrogen content was0.06% by weight (Example 1-14-1). After the heat-treatment at 600° C.,the structure was αFe single phase, and only the existence of the Feelement was observed (Example 1-14-2, FIG. 67, Y3 phase). Y1 phase hasthe amorphous part capable of forming the crystal phase from the resultof Y3 phase.

From the measurement results, the following assessment is made. When thestirring condition upon the deposition reaction was changed, differentphases (X1 phase and Y1 phase) were formed starting from the samestarting material, and the same phase (X3 phase and Y3 phase) was formedafter the heat-treatment at 600° C. The first starting material and thefinal αFe phase are the same, and the difference occurred only in thephase (X1 phase and Y1 phase) after the deposition and the drying, andthus the hydrogen content of the metal-based structure and the formationof the amorphous phase could be controlled by controlling the liquidstate upon the deposition reaction. This is assumed to be the influencecaused by inhibition of application of the mechanical outer force to thedeposited particles as much as possible, as described above.

(Consideration about Formation of Amorphous Phase by Control of HydrogenContent)

Although the detailed explanation is described below, when the mixingmethod upon the deposition reaction was changed, the structure had ahigh hydrogen content and the amorphous single phase was formed when thedropwise addition was performed; whereas, the structure had a lowhydrogen content, and the crystallized parts were partly formed when thestirring was performed. It is considered that when the stirring wasperformed upon the deposition reaction, the binding reaction statebetween Fe and hydrogen was changed to decrease the hydrogen content,whereby a part of the structure was crystallized.

On the other hand, when the amorphous single phase was heated, thehydrogen content was decreased, whereby a part of the structure wascrystallized. It is considered that the crystal phase was formed bydecreasing the hydrogen content. In that case, the structure having ahigh hydrogen content formed the amorphous single phase, and a structurehaving a low hydrogen content was crystallized in part, similarly to theabove.

When the hydrogen content was changed by the two different operations,i.e., the mixing operation upon the deposition reaction, and theheat-treatment, the structure having a high hydrogen content formed theamorphous single phase, and the structure having a low hydrogen contentwas crystallized in part, in both cases. That is, the same results wereobtained by the different operation methods.

Collectively, it is a universal conclusion that the formation of theamorphous phase can be controlled by controlling the hydrogen content,because the formation of the Fe amorphous phase, which has not hithertobeen obtained, was realized by containing hydrogen, and the same causeand effect relationships were obtained in the hydrogen content and theformation of the amorphous phase by the two different operations.

(Measurement 3) SEM Observation

Using a scanning electron microscope (“VE-9800” manufactured by KeyenceCorporation), the metal-based structure obtained in each Example wasobserved (secondary electron beam images). A sample to be measured wasnot subjected to a pre-treatment such as evaporation, and the sample puton a conductive pressure-sensitive adhesive tape pasted on a samplestand was observed as it was. A pressure of a measurement chamber inwhich the material was put was maintained at 10-3 Pa or less. Anacceleration voltage and a working distance at the measurement are shownin a view showing the measurement results. A magnification at themeasurement and a scale bar are also shown in the view.

A short axis length d of the metal-based structure was measured asfollows:

In an SEM image measured, 10 measurement points were selected at random,a short axis length was measured at each measurement point without anytreatment such as binarization, and an average value was obtained. Whenthe metal-based structure was filament-shaped or had an element offilament shape, a width perpendicular to a long axis of the metal-basedstructure was measured as the short axis length d. When the metal-basedstructure was formed of the staple-shaped element or the bead-shapedelement, a short axis length in a part in which the short axis lengthlocated nearest the measurement point is maximum was measured as theshort axis length d at the measurement point.

With respect to the long axis length L of the metal-based structure, alength between both terminals of the metal-based structure was measuredin an SEM image measured, and the obtained length was defined as theminimum value of the long axis length. The measured long axis length Lof the metal-based structure was defined as the length measured orlonger.

The aspect ratio L/d was defined as a value obtained by dividing thelong axis length L by the short axis length d, the short axis lengthbeing obtained at any point at which the long axis length L was measuredin the metal-based structure.

SEM observation results are shown in FIG. 2 to FIG. 38.

The relationships in each Example and view, and the shape classificationof the obtained metal-based structure are as follows:

Example 1-1 FIG. 2 to 5 staple web FIG. 4 is the enlarged view of themiddle part of FIG. 2. Example 1-2 FIG. 6 filament web Example 1-3 FIG.7 filament web Example 1-4 FIGS. 8 and 9 filament web Example 1-4-2FIGS. 10 and 11 filament web FIG. 10 is the enlarged view of the middlepart of FIG. 11. Example 1-4-3 FIGS. 12 to 15 filament web FIG. 14 isthe enlarged view of the middle part of FIG. 13. Example 1-5 FIG. 16bead web Example 1-6 FIG. 17 filament web Example 1-7 FIGS. 18 to 21bead bulk FIG. 19 is the enlarged view of the middle part of FIG. 18FIG. 20 is the enlarged view of the middle part of FIG. 19. FIG. 21 isthe enlarged view of the upper middle part of FIG. 19. Example 1-7-1FIG. 22 bead bulk Example 1-7-3 FIG. 23 bead bulk Example 1-7-4 FIGS. 24and 25 sinter solidified substance of bead bulk FIG. 25 is the enlargedview of the middle part of FIG. 24. Example 1-8 FIG. 26 bead bulkExample 1-9 FIG. 27 bead web Example 1-9-1 FIG. 28 sintered body of beadweb Example 1-9-2 FIG. 29 sintered body of bead web Example 1-10 FIG. 30staple web Example 1-11 FIGS. 31 and 32 filament web FIG. 31 is theenlarged view of the middle part of FIG. 32. Example 1-12 FIG. 33 beadbulk Example 1-12-1 FIG. 34 bead bulk Example 1-12-2 FIG. 35 sinteredbody of bead bulk Example 1-13 FIGS. 36 to 38 bead web FIG. 36 is theenlarged view of the middle part of FIG. 38. FIG. 37 is the enlargedview of the middle part of FIG. 36. Example 1-11-3 FIG. 68 filament webExample 1-11-5 FIG. 69 sintered body of filament web

The short axis length d (average value), the long axis length L and theaspect ratio L/d, obtained from the SEM observation results, are shownas follows:

Example 1-1 FIG. 3

short axis length d: 130 nm

long axis length L: 3.9 μm

aspect ratio L/d: 27

Example 1-2 FIG. 6

short axis length d: 140 nm

long axis length L: 4.0 μm

aspect ratio L/d: 24

Example 1-3 FIG. 7

short axis length d: 150 nm

long axis length L: 3.8 μm

aspect ratio L/d: 21

Example 1-4 FIG. 8

short axis length d: 110 nm

long axis length L: 2.7 μm

aspect ratio L/d: 17

Example 1-4-2 FIG. 10

short axis length d: 130 nm

long axis length L: 2.1 μm

aspect ratio L/d: 17

Example 1-4-3 FIG. 15

short axis length d: 130 nm

long axis length L: 6.9 μm

aspect ratio L/d: 40

Example 1-7 FIG. 20

short axis length d: 250 nm

Example 1-9 FIG. 27

short axis length d: 200 nm

long axis length L: 2.8 μm

aspect ratio L/d: 10

Example 1-10 FIG. 30

short axis length d: 120 nm

long axis length L: 3.8 μm

aspect ratio L/d: 21

Example 1-11 FIG. 31

short axis length d: 110 nm

long axis length L: 5.6 μm

aspect ratio L/d: 52

Example 1-12 FIG. 33

short axis length d: 300 nm

Example 1-13 FIG. 37

short axis length d: 330 nm

long axis length L: 3.7 μm

aspect ratio L/d: 8.1

From the results above, the following can be understood. In the wireshape of the amorphous phase according to the present invention, twomodes of the wire shape, the wire shape based on the filament and thebead wire shape based on the bead are produced, i.e., there are at leasttwo kinds of grown particles corresponding to the two modes of the wireshape and the bead wire shape in the grown particles developing into themetal-based structure. When the magnetic field is applied to thespecific grown particles, the two kinds of shapes, i.e., the wire shapeand the bead wire shape, are obtained depending on the influences of themagnetic property, the shape, the size (the whole size), and the like.The content of the reducible substance dominantly influences the factorto divide the nature of the grown particle into two. Provided that,there is the transitive content regions, and whether it is formed intothe wire shape based on the filament or it is formed into the bead wireshape based on the bead is decided depending on the magnetic fieldstrength there.

In both cases in which the solvent is water and the solvent contains thealcohol, when the content of the reducible substance is 3 mmol/kg ormore, it is easy to obtain the metal-based structure having thefilament-shaped wire shape, and when the content of the reduciblesubstance is less than 60 mmol/kg, it is easy to obtain the metal-basedstructure having the bead wire shape. The threshold values thereof tendto be decreased when the magnetic field strength is strong, i.e., whenthe neodymium magnet is used.

The shapes are further changed by changing the timing at which themagnetic field is applied to the grown particles and the magnetic fieldstrength. The following theoretical formula is obtained.

grown particles 2 kinds×magnetic field action (the presence or absenceof the magnet) 2 kinds=4 modes (filament/staple,bead wire/bead bulk)

Further, variations of middle modes are produced by applying the middlemagnetic field strength or changing the timing of the magnetic fieldaction.

Further, the bead bulk in which the formless phase is produced is formedby increasing the hydrogen content of the metal-based structure oradding the alcohol to the solvent. The formless phase can be formedwithin the range of the content of reducible substance shown inExample 1. In particular, when the content of the reducible substance is0.3 mmol/kg or more and less than 60 mmol/kg, it is easy to form theformless phase. When the solvent contains the alcohol, it is easy toform the formless phase.

The existence of the formless phase is effective for obtaining theminute metal-based structure or the crystallized metal-based structure.

The short axis length of the filament or staple was from about 100 to150 nm, and the remarkable increase thereof by the heat-treatment wasnot observed (Example 1-4-3). The short axis length of the mode in whichthe bead is the basic shape (the bead wire, bead bulk, and bead powder)was from about 200 nm to 300 nm.

With respect to the long axis length, the filament of 10 μm or more, 30μm or more, or 40 μm or more was obtained. In the filament, an aspectratio of 10 or more, 20 or more, 50 or more, or 150 or more wasobserved. In the bead wire, a long axis length of 10 μm or more and anaspect ratio of 8 or more, or 25 or more were obtained.

The metal-based structures having 4 kinds of linear shapes offilament/staple measured had almost the same short axis length d of 110to 130 nm. The tendency in which the filament to which the magneticfield action is applied has a prolonged short axis length, compared tothe staple to which the magnetic field action is not applied is notparticularly observed. From this, it can be considered that the magneticfield action had no influence on prompting the growth in a direction ofthe short axis (Example 1-1, Example 1-4, Example 1-10 and Example1-11).

From the results above, it is considered that after the formed particleswere grown to a certain pre-determined size, they are bound to eachother to form the shape having the long axis direction. In particular,the bead wire has the shape in which the spheres form an almost line inthe long axis direction, and the state in which they are stuck to eachother in the short axis direction is hardly observed, and thus theformation process above can be demonstrated. It is considered that whenthe magnetic field is applied during the binding, the linearity in thelong axis direction was increased, as a result, the wire shape having along length in the long axis direction, and having a high aspect ratio,expressed by long axis length/short axis length was obtained. It isconsidered that the length in the short axis direction was not prolongedin the case in which the magnetic field action was applied, and thus theformed particles were preferentially bound to each other in the longaxis direction, and the binding of the particles in the short axisdirection was not advanced or the advance was extremely decreased.

It can be further considered that the wire having a large curve(winding) like the staple was formed by the influence in which thesubstantial magnetic field effect was decreased by the long elapsed timefrom the deposition (Example 1-2) or the insufficient magnetic fieldstrength (Example 1-3) when the magnetic field was applied, even ifhaving the wire shape.

There were no differences in the shape of the obtained filament in thecomparison of the case in which the magnetic field action was appliedthrough glass with the case in which it was directly applied (Examples1-4 and 1-4-2).

From the results above, the following is understood. When the hydrogencontent was measured as described above for the shape having thecomponent of the wire shape based on the filament, the shape having thecomponent of the bead wire shape, and the shape having a large amount ofthe formless phase, they were confirmed to be the hydrogen-containingmetal-based structure, or the hydrogen-containing amorphous structure.

It became possible to obtain the metal-based structure formed of themetal single phase, or the metal element single phase (for example, theαFe single phase). In particular, it was found that theamorphous-containing substance and/or the hydrogen-containing substancewere effective for obtaining the high purity metal-based structureformed of the metal single phase, or the metal element single phase.

(Relationship between Concentration (Content of Reducible Substance) andHydrogen Content)(S1) Without restrictions on the solvent, when the content of thereducible substance (unit: mmol/kg, hereinafter which is abbreviated to“FS”) was adjusted to 0.3 mmol/kg or more, the metal-based structurehaving a hydrogen content (unit: % by mass, hereinafter which isabbreviated to “H”) of 0.01% by mass (0.4% by atom) or more could beobtained (Example 1-12). The upper limit of the “FS” is the saturatedconcentration, unless otherwise noted.(S2) Without restrictions on the solvent, when FS is 3 mmol/kg or more,H of 0.05% by mass (2.7% by atom) or more is obtained (Example 1-11).(S3) In particular, when the solvent containing water+alcohol was used,FS of 0.3 mmol/kg or more and H of 0.05% by mass (2.7% by atom) or more,0.1% by mass (5.3% by atom) or more, or H of 0.2% by mass (10.1% byatom) or more can be obtained. The hydrogen content, accordingly, isincreased by adding the alcohol to the solvent.(S4) It is a value obtained by diving a molar concentration of hydrogencontained in the hydrogen-containing reducing agent by a valence of themetal-based ion according to the reducible substance, which means ahydrogen concentration per monovalent metal-based ion according to thereducible substance, unit: mmol/kg, which is referred to as “H/+.” Thecontent of the reducing agent (the content of NaBH₄ in Examples), unit:mmol/kg, hereinafter which is abbreviated to “NB.” Without restrictionson the solvent, when H/+ of 6 (NB:3) mmol/kg or more, or H/+ of 20(NB:10) mmol/kg or more, the tendency (S1, S2, or S3) is remarkablyexpressed (Example 2-21, Example 2-14). In both cases of “H/+” and “NB,”the upper limit is the saturated concentration, unless otherwise noted.

From the above, it can be said that the hydrogen content of themetal-based structure according to the present invention can becontrolled by controlling the concentration of the reducible substance.It can be said that the hydrogen content can also be controlled byadjusting the kind and the concentration of the solvent.

(Relationship of Concentration (Content of Reducible Substance),Hydrogen Content and Metal Phase)

(S5) Without restrictions on the solvent, when H is adjusted to 0.01% bymass (0.4% by atom) or more in a case in which FS is 0.3 mmol/kg or moreand H/+ is 20 (NB:10) mmol/kg or more, the formation of oxide issuppressed, thereby to obtain the metal-based structure formed of themetal single phase or the metal element single phase (Example 1-12,Example 2-14, and Example 2-21).(S6) Without restrictions on the solvent, when H is adjusted to 0.05% bymass (2.7% by atom) or more in a case in which FS is 3 mmol/kg or moreand H/+ is 20 (NB:10) mmol/kg or more, the metal-based structure formedof the metal element single phase is obtained (Example 1-11).(S7) In particular, when the solvent containing water+alcohol is used,FS is adjusted to 0.3 mmol/kg or more, H/+ is adjusted to 20 (NB:10)mmol/kg or more, and H is adjusted to 0.05% by mass (2.7% by atom) ormore, 0.1% by mass (5.3% by atom) or more, or 0.2% by mass (10.1% byatom) or more, then the metal-based structure formed of the metalelement single phase is obtained. The solvent containing water+alcoholhas a big effect of increasing the hydrogen content (Example 1-7).(S8) When water is used as the solvent, and FS is adjusted to 0.3mmol/kg or more and less than 14 mmol/kg and H/+ is adjusted to 6 (NB:3)mmol/kg or more and less than 120 (NB:60) mmol/kg, or FS is adjusted to1.0 mmol/kg or more and less than 3.0 mmol/kg and H/+ is adjusted to 20(NB:10) mmol/kg or more and less than 120 (NB:60) mmol/kg, then themetal-based structure containing the intermetallic compound (Fe₂B)formed of the metal and the semi-metal, or the metal-based structureformed of the intermetallic compound (Fe₂B) single phase is obtained(Example 1-12 and Example 2-20).

From the above, it can be said that the composition of the amorphousphase of the metal-based structure according to the present inventioncan be controlled by adjusting the concentration of the reduciblesubstance.

(Relationship between Hydrogen Content and Metal Phase)<Hydrogen Content from S1 to S8>(S9) When H is adjusted to 0.01% by mass (0.4% by atom) or more, themetal-based structure formed of the metal single phase or the metalelement single phase is obtained.(S10) When H is adjusted to 0.05% by mass (2.7% by atom) or more, H isadjusted to 0.1% by mass (5.3% by atom) or more, or H is adjusted to0.2% by mass (10.1% by atom) or more, the high purity metal-basedstructure formed of the metal element single phase is obtained.

From the results above, when the hydrogen content of the metal-basedstructure is changed, the purity of the metal component (the metalelement and/or the semi-metal element) of the crystal phase or in thecrystal phase, included in the metal-based structure or the crystallizedmetal-based structure, is changed. For example, in the comparison of themetal-based structure in which the oxide phase and the metal phase aremixed and the metal-based structure formed of the metal single phase,the purity of the metal component in the latter is higher. Here, themetal phase is a phase formed of the metal element and/or the semi-metalelement, and examples thereof may include a metal element single phase,alloy, a semi-metal, an intermetallic compound, solid solution thereof,a mixture thereof, and a composite thereof. The metal single phase is,as described above, the phase formed of the metal alone, and isexemplified by a phase containing no phase other than the metal phase,such as an oxide. The metal element single phase is a phase formed ofthe metal element alone, including no semi-metal element, and includes aphase formed of a single metal element alone (single metal elementsingle phase) and a phase formed of multiple metal elements. In thelatter, the phase in which multiple phases of the single metal elementsingle phase, alloy phases formed of the metal element, andintermetallic compound phases (in this case, formed of the metal elementalone) are mixed may sometimes be obtained.

For example, in the comparison of the Fe₂B single phase, which is theintermetallic compound single phase, and the αFe single phase, which isthe metal element single phase, the latter contains no semi-metalelement, and thus the latter has a higher purity of the metal elementthan that of the former, and is the metal-based structure with a higherpurity. Similarly, when, in the metal-based structure having theamorphous part, or having the amorphous part and containing hydrogen,the crystal phase after the crystallization is formed of the metalsingle phase or the metal element single phase, it is understood thatthe former has a higher purity of the metal component, and the latterhas a higher purity of the metal element, excluding the hydrogenelement. From this, the metal-based structure formed of the metalelement single phase, and the metal-based structure, which has theamorphous part, has the amorphous part and contains hydrogen, or isformed of the amorphous single phase wherein it is formed of the metalelement single phase by crystallization, are referred to as a “highpurity metal-based structure.” In addition, the metal-based structureformed of the metal single phase, and the metal-based structure, whichhas the amorphous part, has the amorphous part and contains hydrogen, oris formed of the amorphous single phase wherein it is formed of themetal single phase by crystallization, are referred to as a “metal-basedstructure formed of the high purity metal component.”

These phases are assessed by the measurement results in the X-raydiffraction described above. For example, in the X-ray diffractionspectra obtained from the metal-based structures, when only the peakbased on the metal element single phase, for example, αFe single phase,was substantially observed, it was assessed that it was a metal-basedstructure formed of the metal element single phase (αFe single phase).

The purity of the metal component in the metal-based structure,particularly the metal-based structure containing the amorphous part, orthe purity of the metal element is defined by the hydrogen content ofthe metal-based structure or the metal-based structure containing theamorphous part, i.e., the metal-based structure formed of the highpurity metal component can be obtained by adjusting H to 0.01% by mass(0.4% by atom) or more. Further, the high purity metal-based structurecan be obtained by adjusting H to 0.05% by mass (2.7% by atom) or more,to 0.10% by mass (5.3% by atom) or more, or to 0.20% by mass (10.1% byatom) or more. From this, the high purity metal-based structure in whichthe metal element has a high purity can be obtained by increasing thehydrogen content of the metal-based structure. When the metal-basedstructure contains the amorphous part, or is the amorphous single phase,the effect of forming the high purity metal-based structure is greater.The hydrogen content can be controlled by, for example, the control ofthe concentration of the reducible substance, the concentration of thereducing agent or H/+, and further the control of the solventcomposition (Example 1-7, Example 1-11, and Example 1-12).

As shown in Examples, in particular, when Fe is used among theferromagnetic substances, the metal-based structure in which thecrystallization phase is formed of the metal element single phase (αFe)or the intermetallic compound phase (Fe₂B) is obtained at H of 0.01% bymass (0.4% by atom) or more (Example 1-12). Further, the high puritymetal-based structure in which the crystallization phase contains, as amain component, the metal phase (αFe) or is formed of the single phaseof the metal phase (αFe) is obtained at H of 0.05% by mass (2.7% byatom) or more, H of 0.10% by mass or more (5.3% by atom), or H of 0.20%by mass (10.1% by atom) or more (Example 1-11, Example 1-7). Theformation of the formless phase is promoted at H of 0.05% by mass (2.7%by atom) or more, H of 0.10% by mass (5.3% by atom) or more, or H of0.20% by mass (10.1% by atom) or more (Example 1-7). The high puritymetal-based structure in which the crystallization phase is formed ofthe single phase of the metal phase (αFe) is also obtained in that case.The effect above is more remarkably exerted when the solvent containingwater+alcohol is used (Example 1-7).

With respect to the hydrogen content, H of 0.01% by mass (0.4% by atom)or more is obtained at FS of 0.3 mmol/kg or more (Example 1-12). H of0.05% by mass (2.7% by atom) or more is obtained at FS of 3 mmol/kg ormore (Example 1-11). The hydrogen content, accordingly, is increased byincreasing the concentration of the reducible substance (FS). When thesolvent containing water+alcohol is used, H of 0.05% by mass (2.7% byatom) or more, 0.10% by mass (5.3% by atom) or more, or 0.20% by mass(10.1% by atom) or more is obtained at FS of 0.3 mmol/kg or more(Example 1-7). The hydrogen content is increased by adding the alcoholto the solvent as above. The tendency described above remarkably exertsat H/+ of 6(NB:3) mmol/kg or more, and further, the metal-basedstructure formed of the metal phase (αFe) or the intermetallic compoundphase (Fe₂B) is obtained avoiding the formation of the oxide at H/+ of20 (NB:10) mmol/kg or more (Example 2-21 and Example 2-14).

From the results above, the purity of the desired crystal phase or metalelement in the metal-based structure can be defined by the hydrogencontent. It is possible to control the hydrogen content by theconcentration of the reducible substance, the concentration of thereducing agent or H/+, and the solvent composition.

When operations other than Examples are performed, a relationshipbetween the hydrogen content and the control element thereof, and ahydrogen content specified value for obtaining a desired crystallizationphase may be experimentally obtained according to the methods shown inExamples, and the like. Provided that when the metal-based structurecontains hydrogen, the structure contains H in a content of 0.01% bymass (0.4% by atom) or more, H in a content of 0.05% by mass (2.7% byatom) or more, H in a content of 0.10% by mass (5.3% by atom) or more,or H in a content of 0.20% by mass (10.1% by atom) or more, thestructure contains hydrogen in a specified value or more and/or thestructure contains the amorphous part, there is the effect of increasingthe purity of the metal element in the metal-based structure and, at thesame time, there is the effect of controlling the shape of themetal-based structure.

In addition, there is the effect on the formation of the formless phase,when the metal-based structure contains hydrogen, the structure containsH in a content of 0.01% by mass (0.4% by atom) or more, H in a contentof 0.05% by mass (2.7% by atom) or more, H in a content of 0.10% by mass(5.3% by atom) or more, or H in a content of 0.20% by mass (10.1% byatom), the structure contains hydrogen in a specified value or moreand/or the structure contains the amorphous part.

When the composition of the solvent is adjusted, in particular, thealcohol is used as the solvent or the solvent containing the alcohol isused, or water is used as the solvent in which the alcohol is contained,the hydrogen content of the metal-based structure is increased comparedto a case in which water is used as the solvent in Example 1; as aresult, the high purity metal-based structure can be easily produced.Further, the effect of decreasing the cavity ratio of the solidifiedsubstance after the sintering or the crystallization can be promoted bypromoting the formation of the formless phase. The effect above isparticularly effective on the production of the metal-based structureformed of the ferromagnetic substance, and on Fe.

The alcohol is a substance in which a hydrogen atom on the hydrocarbonis substituted by a hydroxyl group (—OH), and examples thereof mayinclude methanol, ethanol, propanol, and the like. The alcohols may beused alone or as a mixture. It is effective that the content of thealcohol is adjusted to less than 90% by mass, relative to the mass ofthe solvent, preferably less than 60% by mass, more preferably less than50% by mass. When the reducible substance is water-soluble, it iseffective to contain the alcohol in water, and usefully, the saturatedconcentration of the reducible substance to the solvent may sometimes becontrolled by adjusting the alcohol content to less than 90% by mass,preferably less than 60% by mass, more preferably less than 50% by mass.In that case, it may be preferable to adjust the alcohol content to arange from 1% by mass or more and less than 50% by mass, it may be morepreferable to adjust the content to a range of 5% by mass or more andless than 50% by mass, and it may be particularly preferable to adjustthe content to a range of 10% by mass or more and less than 40% by mass.In the production of the metal-based structure formed of, particularly,the ferromagnetic substance, or Fe, it is effective to use ethanol asthe alcohol, and in the production of the hydrogen-containingmetal-based structure, the use of ethanol is particularly effective. Itmay sometimes be good to use ethanol as a main component in combinedwith another alcohol such as propanol.

(Measurement 4) DSC

The heat characteristics of the metal-based structures obtained inExamples were measured using a differential scanning calorimetryapparatus (“DSC-60” a pan made of Al, manufactured by ShimadzuCorporation, elevating the temperature at 3° C./minute to 500° C.

The measurement results are shown in FIG. 53 to FIG. 58.

The relationships between each Example and Fig. are as follows:

Example 1-4-1 FIG. 53 Example 1-7 FIG. 54 Example 1-10 FIG. 55 Example1-11 FIG. 56 Example 1-12-1 FIG. 57 Example 1-13 FIG. 58

As described above, the crystallization temperature can be confirmed bythe DSC profile.

(Significance of Heat-Treatment Step)

The metal-based structure formed of the amorphous single phase (X1phase) in Example 1-11 (FIGS. 31 and 47) formed the crystal phase (X2phase) in Example 1-11-3 or 1-11-4 by heat-treatment at 450° C. At thesame time, the hydrogen content was decreased by 40% to X1 phase. Whenit was further subjected to the heat-treatment at 600° C. in additionalExample 1-11-5, the crystal phase became more dominant. It wasconsidered to be the αFe single phase having a high crystallinity, andthere were no elements other than Fe (X3 phase).

From the experimental results above, the following can be understood.The metal-based structure, which was just deposited and dried, was theamorphous substance of Fe containing hydrogen (X1 phase), and when itwas subjected to the heat-treatment, the hydrogen content was decreasedand the αFe crystal phase was formed (X2 phase). When it was furthersubjected to the heat-treatment at a higher temperature, the metal-basedstructure of the αFe single phase having a higher crystallinity (X3phase) was obtained. The hydrogen content of the metal-based structurecan be controlled by the heat-treatment (the decrease of the hydrogencontent). When it is seen from the aspect of the hydrogen content, itcan be said that it was possible to control the amorphous phase (theformation of the crystal phase) by the control (decrease) of thehydrogen content.

From the results of the SEM observation, in the nanowire structure, thehydrogen content was decreased and the large shape change was notobserved after the heat-treatment at 450° C. (FIG. 68) at which thecrystal phase was formed, compared to the structure which was justdeposited and dried (FIG. 31). Further it was observed that the wireswere stuck to each other after the heat-treatment at 600° C. (FIG. 69),and at the same time the decrease of the cavity was observed.

It is effective to perform the heat-treatment so that the temperature ismaintained at a temperature at which the heat generation is observed inthe DSC analysis on the formation of the crystal phase. At that time, itmay sometimes be more effective to perform the treatment in a reducedpressure or in a vacuum atmosphere on the decrease of the hydrogencontent and/or the promotion of the crystallization. It is also possibleto control the hydrogen content and/or the crystallization of themetal-based structure by controlling the heat-treatment temperature andatmosphere.

2. Example 2

As shown in Table 4, as in Example 1, the aqueous iron sulfate solutionshaving a different concentration and the aqueous solution containing thereducing agent (NaBH₄), having a different concentration were prepared,and the aqueous reducing agent solution was added dropwise to theaqueous iron sulfate solution at room temperature to obtain the deposit.As described above, the concentration fluctuation of the reduciblesubstance at the dropwise addition can be decreased by adding thereducing component to the solution of the reducible substance, wherebythe metal-based structure can be stably formed.

As the solvent of the aqueous solution, water was used.

After the dropwise addition of the aqueous reducing agent solution wasfinished, the liquid was allowed to stand for 15 minutes, and aneodymium magnet-2 was brought into contact with an outer bottom face ofthe beaker to obtain deposit. The washing was performed in the washingcondition 1 once or more while the state in which the magnet was broughtinto contact with the beaker was maintained. After the washing, themagnet was separated, the deposit remaining on the bottom face of thebeaker was put in a glass tube whose one side was sealed, and was driedin the drying condition 1. While the exhaust ventilation in the glasstube by the rotary pump was continued, the heat-treatment was performedin the heat-treatment condition 1 in which the heat temperature waschanged to 150° C. and the retention time was changed to 2 minutes.

After that, while the exhaust ventilation was continued, the glass tubewas vacuum-sealed in a state in which the substance was put in the glasstube. The glass tube was maintained at 600° C. for 60 minutes using anair atmosphere furnace with a temperature elevation rate of 20°C./minute, and was cooled to room temperature in the furnace. After theheat-treatment, the substance in the glass tube was obtained as acrystallized metal-based structure (Example 2-1 to Example 2-20). InExample 2-21, after the dropwise addition of the aqueous reducing agentsolution was finished, the liquid was allowed to stand for 15 minutes,and the resulting liquid was filtered. The filtered deposit was washedin the washing condition 1. After the washing, the deposit was put in abeaker, which was dried in a desiccator to obtain a metal-basedstructure.

An X-ray diffraction spectrum of the metal-based structure obtained asabove was measured in the same manner as in Example 1, whereby thecrystal phase was examined. The results are shown in Table 4.

Example 2-12 and Example 2-19 were respectively quoted from Example1-11-1 and Example 1-12-2, wherein the operation conditions are asdescribed above.

In Table 4, a volume ratio was calculated based on a volume of the ironsulfate solution in which 1 kg of the solution containing the ironsulfate was assumed to be 1 L and 1 kg of the solution containing NaBH₄was assumed to be 1 L.

Symbols showing the crystal phase in Table 4 have the followingmeanings.

F: αFe single phaseF/(B): mainly formed of αFe and a slight amount of Fe₂B was mixedF—O: mixture of αFe and Fe oxideF/B: mixture of αFe and Fe₂BFB: Fe₂B single phaseFO: Fe oxide

TABLE 4 Aqueous iron sulfate solution Aqueous Reducing agent (NaBH₄)solution Solution Solution Solution concentration Volume concentrationconcentration conversion ratio Solvent Based on Solvent Based on H Basedon Water solvent Water solvent concentration H/+ iron sulfate CrystalExample [g] [mol/kg] [g] [mol/kg] [mol/kg] [mol/kg] [L/L] phase 2-1 131.4E+00 15 3.5E+00 1.4E+01 7.0E+00 1.1E+00 F 2-2 13 1.4E+00 12 1.0E+004.1E+00 2.0E+00 9.0E−01 F 2-3 13 1.4E+00 25 6.3E−01 2.5E+00 1.3E+001.9E+00 F 2-4 13 1.4E+00 25 6.3E−02 2.5E−01 1.3E−01 1.9E+00 F 2-5 161.0E−01 12 1.0E+00 4.1E+00 2.0E+00 7.4E−01 F/(B) 2-6 16 6.7E−02 203.6E+00 1.4E+01 7.1E+00 1.2E+00 F 2-7 16 6.7E−02 12 1.0E+00 4.1E+002.0E+00 7.4E−01 F/(B) 2-8 16 6.7E−02 6 1.0E+00 4.1E+00 2.0E+00 3.7E−01 F2-9 16 6.7E−02 24 1.0E+00 4.1E+00 2.0E+00 1.5E+00 F 2-10 16 6.7E−02 256.3E−01 2.5E+00 1.3E+00 1.5E+00 F 2-11 16 6.7E−02 15 3.5E−01 1.4E+007.0E−01 9.3E−01 F 2-12 16 6.7E−02 25 6.3E−02 2.5E−01 1.3E−01 1.5E+00 F2-13 16 6.7E−02 110 1.4E−02 5.8E−02 2.9E−02 6.8E+00 F/B 2-14 16 6.7E−02125 6.3E−03 2.5E−02 1.3E−02 7.7E+00 F-O 2-15 16 1.3E−02 15 3.5E+001.4E+01 7.0E+00 9.4E−01 F 2-16 48 1.3E−02 45 7.0E−02 2.8E−01 1.4E−019.4E−01 F/(B) 2-17 480 2.7E−03 15 3.5E+00 1.4E+01 7.0E+00 3.1E−02 F/B2-18 480 2.7E−03 75 6.3E−01 2.5E+00 1.3E+00 1.6E−01 F/B 2-19 120 2.7E−0360 2.6E−02 1.1E-01 5.3E−02 5.0E−01 FB 2-20 480 2.7E−03 440 1.4E−025.8E−02 2.9E−02 9.2E−01 FB 2-21 360 2.7E−03 930 2.6E−03 1.0E−02 5.1E−032.6E+00 FO

As shown in Table 4, when the concentration of an aqueous reducing agentsolution was excessively low, the reduction of Fe ions in the aqueousiron sulfate solution did not appropriately occur, and the peakbelonging to the Fe oxide appeared in the X-ray diffraction spectrum ofthe metal-based structure. When the concentration of an aqueous ironsulfate solution was not excessively low, αFe was confirmed byincreasing the concentration of an aqueous reducing agent solution, andwhen the concentration of an aqueous iron sulfate solution is 15 mmol/kgor more, only the peak belonging αFe appeared in the X-ray diffractionspectrum of the metal-based structure (FIG. 65 (Example 2-12), FIG. 59(Example 2-3)). When the concentration of an aqueous reducing agentsolution is excessively high, not only the peak of αFe but also the peakbelonging to Fe₂B appeared in the X-ray diffraction spectrum of themetal-based structure (FIG. 60 (Example 2-7)). When the concentration ofan aqueous iron sulfate solution is excessively low, only the peakbelonging to Fe₂B appeared in the X-ray diffraction spectrum of themetal-based structure (FIG. 50 (Example 2-19)).

Summarizing the results above, the effects caused by the concentrationof an aqueous iron sulfate solution and the concentration of an aqueousreducing agent solution on the crystal phase or the composition of themetal-based structure can be shown as in FIG. 61. It is considered that,in a part near to a border in each region, the composition is changeddue to the influence of adjacent regions. Specifically, at a part nearto a border between a region of αFe and a region of Fe oxide, there is amixed part in which both αFe and Fe oxide exist, as shown in Example2-14.

Example 2-12 is quoted from Example 1-11-1.

Example 2-19 is quoted from Example 1-12-2.

In the results described below, the upper limits of “FS” and “NB” (theconcentration of an aqueous reducing agent solution) are both thesaturated concentration, unless otherwise noted. The upper limit is asaturated concentration, unless otherwise noted. The saturatedconcentration at room temperature in FS and NB were respectively 1.4mol/kg and 14 mol/kg (H/+:28 mol/kg).

(S11) When FS is 3 mmol/kg or more, and H/+ is 20 (NB:10) mmol/kg ormore, then the metal phase containing mainly αFe is obtained.(S12) When FS is adjusted to 3 mmol/kg or more, H/+ is adjusted to 20(NB:10) mmol/kg or more, and H is adjusted to 0.05% by mass (2.7% byatom) or more, then the metal phase containing mainly αFe is obtained(Example 2-12, and Example 1-11-2).(S13) When FS is 15 mmol/kg or more, and H/+ is 30 (NB:15) mmol/kg ormore and less than 2000 (1000) mmol/kg, then the αFe single phase ofhigh purity metal phase is obtained as the crystallization phase.(S14) When FS is adjusted to 15 mmol/kg or more, H/+ is adjusted to 30(NB:15) mmol/kg or more and less than 2000 (1000) mmol/kg, and H:0.05%by mass (2.7% by atom) or more, then the αFe single phase of high puritymetal phase is obtained as the crystallization phase (Example 2-12 andExample 1-11-2).(S15) When FS is 15 mmol/kg or more and less than 150 mmol/kg, and H/+is 30 (NB:15) mmol/kg or more and less than 2000 (NB:1000) mmol/kg, thenthe αFe single phase of high purity metal phase is obtained as the morestable crystallization phase.(S16) When FS is adjusted to 15 mmol/kg or more and less than 150mmol/kg, H/+ is adjusted to 30 (NB:15) mmol/kg or more and less than2000 (NB:1000) mmol/kg, and H is adjusted to 0.05% by mass (2.7% byatom) more, or H is adjusted to 0.1% by mass (5.3% by atom) more, thenthe αFe single phase of high purity metal phase is obtained as the morestable crystallization phase (Example 2-12 and Example 1-11-2).

The deposition performed in a state in which FS is a value near to thesaturated concentration or FS is in an oversaturation state ispreferable in terms of the operation, because it is easy to adjust FS toa certain range. It is possible to adjust the saturated concentration byadjusting the composition of the solvent.

As shown in Table 4, a basic tendency is that when the concentration ofthe aqueous reducing agent solution is a certain value or more and thevolume ratio is large, the crystallized metal-based structure having αFesingle phase is obtained. Although the upper limit of the volume ratiois not particularly limited, it is preferably 5.0 or less, morepreferably 2.0 or less.

Specifically, as shown in FIG. 62, the following two threshold values,N-1 and N-2 could be set for the concentration of an aqueous reducingagent solution.

N-1 is H/+:14 (NB:7) mmol/kg.

N-2 is H/+:60 (NB:30) mmol/kg.

The following 5 threshold values, L-1 to L-5 could be set for the volumeratio.

L-1: 0.02 L-2: 0.2 L-3: 0.6 L-4: 0.8 L-5: 1.0

When the threshold values were N-1 or more and L-1 or more, the metalsingle phase having no oxide was obtained.

When the threshold values were N-2 or more and L-2 or more, the metalphase (αFe) was obtained.

When the threshold values were N-2 or more and L-3 or more, it was easyto obtain the metal phase (αFe).

When the threshold values were N-2 or more and L-4 or more, it waseasier to obtain the metal phase (αFe).

When the threshold values were N-2 or more and L-5 or more, it wasparticularly easy to obtain the metal phase (αFe).

3. Consideration 3-1. Control of (i)-(iii) by H % Control (i) Formationof Amorphous Phase (Dropwise Addition/Stirring and Heat-Treatment)<Consideration 1> <Consideration 4>

The mixing method during the deposition reaction was changed (Example1-11). In the case of the dropwise addition, the hydrogen content washigh, i.e., 0.1% by weight (5.3 at %), and the Fe amorphous single phasewas formed (Example 1-14), and in the case of the injection mixing andthe stirring, the H content was low, i.e., 0.06% by weight (3.2 at %)and a part of the Fe amorphous substance was crystallized. It isconsidered that the binding reaction state between Fe and H was changedby stirring the system during the deposition reaction to decrease the Hcontent, whereby a part of the amorphous substance was crystallized<Consideration 1>.

On the other hand, (Example 1-11-3), the amorphous single phase washeated to decrease the H content, and a part of the Fe amorphoussubstance was crystallized at 0.06% by weight (3.2 at %). It isconsidered that the H content was decreased by the heating to change thebinding reaction state between Fe and H, whereby the crystal phase wasformed. In that case, similarly to the above, the amorphous single phasewas formed in the case of the high H content; whereas, a part of theamorphous substance was crystallized in the case of the low H content<Consideration 4>.

When the H content was changed by the two different operations, i.e.,the mixing operation during the deposition reaction, and the heatingtreatment, the amorphous single phase was formed in the case of the highH content; whereas, a part of the amorphous substance was crystallizedin the case of the low H content in both operations. That is, the sameresults were obtained by the different operation methods.

Summarizing the above, the formation of the Fe amorphous phase could berealized by containing H, wherein it had hitherto been difficult to formthe Fe amorphous phase. Further, the amorphous phase containing thecrystal phase in part was formed by decreasing the hydrogen content inthe two different operations. As the same cause and effect relationshipscould be obtained in the different operations, it was concluded as theuniversal conclusion that the formation of the amorphous phase could becontrolled by controlling the hydrogen content.

The effects above are large when the metal-based structure has an H % of2.0 at % or more (m≤30, for reference), and further the effects arelarger when the structure is, in addition to the H % above, formed ofthe metal element, or the single element metal (Fe). When the H contentis 0.061% by weight (3.3 at %) or more, 0.075% by weight (4.0 at %) ormore, or 0.095% by weight (5.04 at %) or more, the amorphous singlephase containing hydrogen, formed of the metal element or formed of thesingle element metal (Fe), are obtained.

The present application provides the method for controlling theformation of the amorphous phase of the metal-based element, metalelement, and single element metal, which is difficult to cause not onlyin a usual equilibrium reaction but also in non-equilibrium reactionsuch as a rapid solidification processing of melted metal. Inparticular, the formation of a compound of Fe with H has not been found,and the solid solution of H is known but it has hitherto been known thatit is very difficult to form a combined state of Fe—H. In the presentapplication, the formation of the Fe amorphous phase containing hydrogenis deduced that the crystallization of Fe is inhibited by exhibiting aspecific bound reaction state of Fe and H, which has not hitherto beenconsidered, as a result, whereby the Fe amorphous phase is formed(amorphized) by containing hydrogen. As the specific bound reactionstate can be formed in Fe, which is the element having a very lowbinding reactivity with H, the method for controlling the hydrogencontent and the method for controlling the formation of the amorphousphase of the present application are effective for other metal elementshaving a reactivity with H equal to or stronger than Fe.

(ii) Particle Shape Control (Control of Shaped/Formless Shape)<Consideration 3>

In the comparison of Examples 1-12, 1-11 and 1-7, the H contents wererespectively 0.02% by weight (0.81 at %), 0.10% by weight (5.3 at %) and0.22% by weight (11.0 at %), and the particle shape was shaped (300B),shaped (100F), or has 300B+formless phase. From the above, it wasunderstood that the formless phase could be formed by increasing the Hcontent. Specifically, when the H content is more than 0.10% by weight(5.5 at %), 0.12% by weight (6.5 at %) or more, or 0.19% by weight (9.4at %) or more, the formless phase-forming efficiency is increased.Conversely, when the H content is 0.27% by weight (13 at %) or less,0.19% by weight (9.4 at %) or less, or 0.10% by weight (5.5 at %) orless, the shaped phase (shaped particle)-forming efficiency isincreased. The H content is controlled by the solvent control, wherebythe particle shape (shaped/formless) can be controlled. In particular,when the alcohol or ethanol is contained in the solvent, the controlefficiency may sometimes be increased. Combining it with the results inConsideration 5 described below, when the H content is 0.037% by weight(2.0 at %) or more and 0.27% by weight (13 at %) or less, theself-granulating reaction particles having a particle size of 500 nm orless, and containing mainly the metal element or formed of the singleelement metal (Fe) are formed. When the H content is 0.037% by weight(2.0 at %) or more and 0.19% by weight (9.4 at %) or less, or 0.10% byweight (5.5 at %) or less, the self-granulating reaction particleshaving a particle size of less than 175 nm, and containing mainly themetal element or formed of the single element metal (Fe) are formed.

(iii) Composition Control <Consideration 5>

(Example 1-12) When the concentration of the reducible substance (FS),FS_Low was 2.7 mmol/kg and H % was 0.02% by weight (0.81 at %), themetal-based (Fe₂B composition) amorphous single phase was obtained.(Example 1-11) When FS_High was 67 mmol/kg and H % was 0.10% by weight(5.3 at %), the metal (Fe) amorphous single phase was obtained. (Example1-7) In the condition in which ethanol was added to the solvent, whenFS_Low was 2.7 mmol/kg and H % was 0.22% by weight (11.0 at %), themetal (Fe) amorphous single phase was obtained.

When the H % of the metal-based structure is increased by “solutecontrol,” i.e., by changing the concentration of, mainly, the reduciblesubstance, a metal-based structure formed of the metal element, or thesingle element metal (Fe), containing no semi-metal element is obtained.When the “solvent control” is performed, i.e., the H % of themetal-based structure is increased by adding ethanol to water of asolvent, the same metal-based structure formed of the metal element, orthe single element metal (Fe), containing no semi-metal element isobtained.

The H % control and the composition control can be performed by adifferent operation, the “solute control” or the “solvent control”; inother word, it is possible “to control to the high purity metalcomposition formed of the metal element, containing no semi-metalelement, or the metal single element composition (Fe) by increasing theH %.” It is judged that “to control the composition by the H % control”and “to control to the high purity metal composition formed of the metalelement, or the metal single element composition (Fe) by the increase ofthe H %” are universal results, because the same cause and effectrelationship can be obtained by the different operation.

Considering Consideration 1 and Consideration 4 together, in Example1-14 and Example 1-11-3, when the H % was 0.06% by weight (3.2 at %),the Fe metal-based structure containing the amorphous phase wasobtained, and thus when H % is 0.018% by weight (1.0 at %) or more,0.037% by weight (2.0 at %) or more, or 0.056% by weight (3.03 at %) ormore, the metal-based structure formed of the metal element or the metalsingle element composition (Fe), or the metal-based structure having theamorphous phase at least in part, which is formed of the metal elementor the metal single element composition (Fe) is obtained.

3-2. H Cluster

Example 1-11 (FS_High, Solvent Water) is considered as described below.<Consideration 2>

(a) It is difficult to form the stable amorphous phase for Fe atoms, butthe stable amorphous phase containing H was formed in the presentapplication.(b) In the Fe amorphous phase, a lot of (5.29 at %) H atoms are stablycontained in a non-diffusion state.(c) The formation of the hydrogen compound is not confirmed from Fe.(d) In the amorphous phase (Example 1-11) of the present application,the crystallization is performed by the heat-treatment, whereby the αFesingle phase is formed.(1) From (c), the strong binding reaction state is not formed between Feand H in the state of equilibrium which has conventionally been known.From (a), (b) and (c), the specific reaction bound state between Fe andH, which cannot be explained by the usual state of equilibrium, isformed, in view of the high hydrogen content and the stable amorphousphase.(2) From the result (d), the impurity components such as B in thesolution are excluded, and the specific atomic structure (composition)containing Fe and H is obtained.(3) In Example 1-11-2, the hydrogen content in the amorphous singlephase was 5.29 at %, and the ratio of Fe:H was 20:1.12.

As a result of the study of the H mix proportion in Examples, the atomicmix proportion of M (metal-based atom) to H (hydrogen atom) wasexpressed as M:H=m:1 wherein m is an integer and m≥3. The mix proportionis a mix proportion of the aggregate or cluster, or nanoparticle ormetal-based structure of the reduction deposited substance, and all ofthe 6 metal-based structures, whose H contents were measured inExamples, conform to the condition in which “m:1, m is an integer, andm≥3.” In Examples other than Example 1-12, as the αFe single phase wasformed, from the XRD results after the heat-treatment, % by weight wasconverted to at %, defining the metal-based atom as the Fe atom and theparent phase as Fe, and the m number (mix proportion) was obtained fromthe at % of Fe and the at % of H. In Example 1-12, as the Fe₂B singlephase was formed, the m number was obtained defining the parent phase asFe₂B. The measurement results are that M:H were, from top to bottom ofExamples in Table 5 below, 8:0.98, 20:1.12, 30:1.01, 30:1.01, and120:0.98. From the results above, the m number of M:H=m:1 were obtainedas, from the top, 8, 20, 30, 30, and 120. In Example 1-12-1 (the bottomcolumn in Table 5), as the parent phase is Fe₂B, m was, respectively,40, 80 and 120 relative to the intermetallic compound (Fe₂B), the metalatom (Fe), and the metal-based atom (Fe+B).

TABLE 5 Parent phase H wt % H at % Fe at % B at % m m:X 1-7-2 Fe 0.2210.96 89.04 —  8 0.98 1-11-2 Fe 0.10  5.29 94.71 —  20 1.12 1-14-1 Fe0.06  3.24 96.76 —  30 1.01 1-11-3 Fe 0.06  3.24 96.76 —  30 1.01 1-12-1Fe₂B 0.02  0.81 66.13 33.06 120 0.98

From the results above, all the cases conform to the “integer rule”;that is, the planar or three-dimensional structure in which one H(hydrogen) atom exists at the center and the metal atoms are disposedoutside is suggested. When the structure is formed of the metal elementor the metal single element (Fe), they conform to a “regular polyhedronrule (described below).” (Regular polyhedron rule: m=4, 6, 8, 12, 20,30.) From the conclusion, the existence of the compound or cluster,having the regular polyhedron structure or the structure having the sameshort distance regularity, was concluded.

Definition of Cluster: “A substance in which several to several tens ormore atoms or molecules are bounded to each other by an interaction.”

“H cluster” means a cluster formed of the metal-based atom and hydrogen,of the present application, including the metal-based structure,nanoparticle, or cluster having a mix proportion of M_(m)H wherein M isa metal-based atom, and m is an integer, m≥3. The shaped nanoparticlehas the specific mix proportion and is the aggregate, and thus it can besaid to be the H cluster.

“Metal H cluster” means the structure, nanoparticle, or cluster formedof the metal element, or the metal single element (Fe).

3-3. “Reaction Circumstance Control”

With respect to the same Examples (Comparison of Examples 1-11 and 1-14)stated in (i) amorphous phase formation by the H % control<Consideration 1>, production conditions to form the amorphous phase bythe H % control is described. This is the detailed explanation about“Dropwise Addition/Stirring.”

The formation of the amorphous phase can be promoted by the “quietreaction”; in other words, the H % content can be controlled and theformation of the amorphous phase can be controlled by the “reactioncircumstance control.” Further, the m number of the clusters can becontrolled, whereby the metal-based structure and the physicalproperties of the nanoparticles can also be stably formed. The reactioncircumstance control is also an important factor concerning theself-granulating reaction, and the physical properties of the shapedparticle can be stably formed by “quiet reaction,” as in the formationof the amorphous phase.

The same “solution” was used, and the rate of change C in the reactioncircumstance (described below) was changed. There was a difference inthe amorphous phase after the drying. After the heat-treatment at 600°C., αFe was formed in both cases. Only the formation of the amorphousphase could be controlled (amorphous single phase or partlycrystallized) by changing the rate of change C in the reactioncircumstance. (1) When C was adjusted to 0.4252, the amorphous singlephase of the single element metal (Fe) having a hydrogen content, H % of0.10 and m of 20 was obtained. (2) When C is adjusted to 2.5781, theamorphous phase-containing single element metal structure was obtainedwhich had an H % of 0.06, and an m of 30, was the single element metal(Fe) amorphous phase+αFe, and had a crystallized part in part.

The reaction circumstance control is to control the change during thereaction in the comparison with a standing state before the reaction(difference from the standing state), and is a very important controlfactor for obtaining the pre-determined effects of the presentapplication. When the change of the pressure [Pa], temperature [K], andmagnetic field effect [T] of the solution during the reaction arecontrolled to values sufficiently small (<1E(−4)), for example, when thetemperature is a normal temperature, the pressure is a normal pressure,and there is no change in the magnetic field effect (a permanent magnetis fixed) as in Examples, the “reaction circumstance control” isperformed by controlling amounts of change in the “volume factor” andthe “stirring factor” to specific values or less.

“Volume Factor”

Volume Element V [1/second]:A rate of increase in the volume by mixing: V=V2/V1/timeA rate of increase in the volume by mixing: V2/V1/time [1/second]Amount of increase in the volume by mixing: V2/time [mL/second]

“Stirring Factor”

It is defined by a stirring element S [1/second]: a stirring speed, arevolution speed (the number of revolutions) of a rotor, the number ofvibrations of the solution, a moving velocity of the solution, and thelike. S [1/second]: the number of revolutions of a rotor [1/second], thenumber of vibrations [1/second] in the case of the solution vibration.Sv [mm/second]: the maximum speed of a rotor [mm/second], the maximummoving velocity [mm/second] (the moving velocity is a speed to a vessel)in the case of the moving of the solution. When there is a steady flow,a relative velocity to the steady flow [mm/second], Sv, is appropriatelyconverted to S. S=Sv/(2πr), Sv=2πrS wherein r is a radius of a rotor.

TABLE 6 Volume factor Stirring factor Example V1 V2 time V V2/time S SvNo. mL mL s 1/s mL/s 1/s mm/s 1-11 Dropwise 16 25 300 0.0052 0.0833 0.4240 addition Dropwise addition Generation of bubbles 1-14 Stirring 48 75 20 0.0781 3.7500 2.5 236 Injection Stirring with glass rod V: VolumeElement, evaluates the mixed state of the solution. V = V2/V1/time, V1:a volume of a reducible solution, V2/time: a dropwise addition rate of areducing agent S: Stirring Element, evaluates the stirring state of thesolution. S: a stirring speed, the number of revolutions [1/second], Sv:the maximum speed of a rotor [mm/second] Sv = 2πr5 (r: a radius of arotor)

In Example of stirring (Example 1-14), the middle part of the beakerhaving an inner diameter of about 60 mm was stirred at a rotation of φ30 mm using a glass rod. In Example wherein r=15 mm, the dropwiseaddition was S=2.5 [1/second] (2.5 revolutions per second) (Example1-11), as a result of the observation, the moving velocity of thebubbles introduced by the dropwise addition of the reducing agentimmediately after the dropwise addition was 40 [mm/second]. The slightstirring occurred by the movement of the bubbles. The stirring elementwas obtained from the moving velocity of the bubbles. The results wereobtained from Sv=40 [mm/second] (measurement), the stirring element:S=Sv/(2πr)=0.42 [1/second], and r=15. The results are shown in Table 6.

C: Rate of change in the reaction circumstance (the total of the ratesof change influencing the change of the deposition reaction) [1/second]

C=Σ(V+S+P+T+m+ . . . )

When the mixing method was changed during the deposition reaction, inthe case of the dropwise addition (Example 1-11), the hydrogen contentwas high and the amorphous single phase was formed, and in the case ofthe injection mixing and the stirring (Example 1-14), the H content waslow and the crystallization occurred in part. When the rate of change Cin the reaction circumstance was 3.1 [/second] or less, i.e., the totalof the change elements in the reaction circumstance, C=V+S, was 3.1 orless, the amorphous phase-containing substance was obtained which had anH % of 2.0 at % or more or 2.7 at % or more, having an m number of 41 orless or 30 or less, and was formed of the metal element or the metalsingle element.

When C was adjusted to 2.47 or less, or V was controlled to 0.07 or lessand S was controlled to 2.4 or less, or V was controlled to 0.07 or lessand Sv was controlled to 200 or less, the amorphous single phase wasobtained which had an H % of 3.3 at % or more or 4.1 at % or more, andan m number of 29 or less or 20 or less, and was formed of the metalelement or the metal single element.

When C was controlled to 2.47 or less, or V was controlled to 0.07 orless and S was controlled to 2.4 or less, or V was controlled to 0.07 orless and Sv was controlled to 200 or less, the shaped particles werestably formed by the self-granulating reaction {e.g., refer to Example1-11 (the shaped particle 100F) and Example 1-12 (the shaped particle300B)}. In order to stably advance the self-granulating reaction, thesame conditions as the formation condition of the amorphous single phaseare preferable.

3-4. “Threshold Values” and H %, m Number (Selectively Formed m Numberof 30 or More/or Less)

The binding reaction state of the metal element or semi-metal elementand H, the metal element and H, or the Fe and H as shown in Examples, isselectively controlled by changing, in addition to the “reactioncircumstance control,” the “solution control,” in particular, aconcentration of the reducible substance (FS concentration); as aresult, the hydrogen content in the metal-based structure, nanoparticleor cluster is controlled, and the specific mix proportion (the m number)is controlled. Further, the particle shape, i.e., the hydrogen content,composition and crystal structure, shape and size of the particle, canalso be controlled.

In the present application, the existence of a “threshold value T of aconcentration of the reducible substance” for controlling the hydrogencontent, or controlling the m number has been found. (Example 1-11) At athreshold value T or more, the H % is controlled to 2.0 at % or more andm controlled to m≤30 or less, and a structure, nanoparticle, or cluster(metal H cluster), formed of the metal element or the metal singleelement (Fe) can be formed. (Example 1-12) At a less than thresholdvalue T, the H % is controlled to less than 2.0 at % and m is controlledto m≥31, and a metal-based structure formed of an Fe₂B composition canbe formed. The “threshold value T can be controlled” by the solventcontrol. (Example 1-7) The threshold value is decreased by adding analcohol (or ethanol) to a solvent, and at a threshold value T or more,the H % is controlled to 2.0 at % or more and m is controlled to m≤30,or the H % is controlled to 9.0 at % or more and m is controlled to m≤8,and a formless phase in which shaped particles 300B are mixed is formed,and a structure formed of the metal element, or the structure formed ofthe single element metal (Fe) are obtained. In Examples in the presentapplication, when the solvent is water, the threshold value is 0.21% ofthe saturated concentration, or 3 mmol/kg, and when an alcohol is added,the threshold value is decreased to 1/10 and is 0.3 mmol/kg. The amountof the alcohol added of 1% by weight or more is effective. When thesolvent is ethanol, the effect may sometimes be further increased.

When the concentration (metal ion concentration) of the reduciblesubstance is adjusted to the threshold value or more, a structure,nanoparticle, or cluster (“metal H cluster”) may sometimes be producedwhich consists of the metal element, or the single element metal (Fe),without the semi-metal. The threshold value relates to the clustercomposition (metal element) and does not necessarily correspond to theparticle shape.

There is a strong interrelationship between the FS concentration and theparticle shape. There is a case in which the size of the shaped particledoes not change depending on the kind of the solvent. In Examples in thepresent application, the addition of the alcohol to the solventdecreased the threshold values of the H % and the m number, but did notchange the size of the shaped particle. (Example 1-12) before theaddition (the solvent was water), the shaped particle was 300B at aconcentration of the reducible substance of 2.7 mmol/kg, and (Example1-7) in the case of addition of the alcohol to the solvent, the shapedparticle was 300B at a concentration of the reducible substance of 2.7mmol/kg. The size of the shaped particle was not changed by the changeof the solvent.

There is a strong interrelationship between the FS concentration and them number at a threshold value or more. In the structure, nanoparticle or(metal) cluster formed of the metal element, or the single element metal(Fe), formed at the threshold value or more, a product having a lowerthe H % content and a larger the m number is formed with increase of theconcentration of the reducible substance, and the H % content and the mnumber, respectively, negatively and positively correlate to theconcentration of the reducible substance; in other words, the tendencyis observed in which the metal component is increased and the hydrogencontent is decreased in the structure with increase of the concentrationof the reducible substance.

5. Control of Shaped Particle Shape, Self-Granulating Reaction, andMagnetic Field Alignment <Consideration 2>

In Examples of the present application, it was found that there was aninterrelationship between the concentration of the reducible substance(FS) and the particle shape. As shown in Examples below, the “shapedparticles” having uniform characters, such as the shape and the size, ofeach of 100F and 300B in FS_High and FS_Low are formed. The features ofthe characters are that (1) they have the uniform shape and size; (2)they have the specific composition; (3) they are the amorphous phase;and (4) they have the specific amorphous phase structure (the DSCresults are different).

The results are compared below.

(Example 1-11) In the condition in which a concentration of thereducible substance (FS) was FS_High: 67 mmol/kg and the solvent waswater, the amorphous single phase having a hydrogen content, H %, of0.10% by weight and a mix proportion, m, of 20, formed of 100F shapedparticles, and having the single element metal (Fe) composition, fromXRD results, was obtained. DSC results: two peaks of heat generation.

(Example 1-12) In the condition in which a concentration of thereducible substance (FS) was FS_Low: 2.7 mmol/kg and the solvent waswater, the amorphous single phase having an H % of 0.02% by weight andan m of 40, 80, 120, formed of 300B shaped particles, and having theFe2B composition, from XRD results, was obtained. DSC results: one ofendothermic change and one peak of heat generation.

(Example 1-7) In the condition in which a concentration of the reduciblesubstance (FS) was FS_Low: 2.7 mmol/kg and the solvent waswater+ethanol, the amorphous single phase having an H % of 0.22% byweight and an m of 8, formed of 300B+formless phase, and having thesingle element metal (Fe) composition, from XRD results was obtained.DSC results: one endothermic change and one peak of heat generation.

(1) The shape and the size are uniform.

When the metal-based structure is based on the shape of staples orfilaments, particles having uniform sizes between 110 and 150 nm(referred to as “100 F”) are observed. When the metal-based structure isbased on the bead shape, particles having uniform size from 200 to 330nm (referred to as “300B”) are observed.

(2) To have a specific composition. <Consideration 2>

(Example 1-11) 100F shaped particles, and the single element metal (Fe)composition from XRD results after the heat-treatment. (Example 1-12)300B shaped particles, and the intermetallic compound Fe₂B compositionfrom XRD results after the heat-treatment. (Example 1-7) 300B (+formlessphase), and the single element metal (Fe) composition from XRD resultsafter the heat-treatment.

From the XRD measurement results after the heat-treatment, when thecomposition of the metal-based element other than H is observed, it iscontrolled to the specific composition of the metal element singleelement (Fe) or the intermetallic compound (Fe₂B); that is, it iscontrolled to either the single element metal or the intermetalliccompound composition, and there is no mixture. In Example 1-7, theformless phase is contained, but the αFe single phase is formed as awhole, and thus 300B in Example 1-7 is also the single element metal(Fe) composition, concerning the metal-based element.

(3) It is the amorphous phase. (4) The specific amorphous phasestructure exists (DSC results are different). (Example 1-11) 100F shapedparticles and the amorphous single phase, DSC results: two peaks of heatgeneration, (Example 1-12) 300B shaped particles and the amorphoussingle phase, DSC results: one endothermic change and one peak of heatgeneration. It is understood that the two kinds of the shaped particlesare both the amorphous single phase, but are different in the amorphousphase structure from the DSC results.

These shaped particles are formed by advance of the self-granulatingreaction in a manner in which the H % is controlled by the “reactioncircumstance control” in addition to the control of the concentrationof, in particular, the reducible substance in the “solution control.”The self-granulating reaction particles, accordingly, are formed byspontaneous growth of the aggregate until a specific character is formedby the self-granulating reaction. The formation of particles havinguniform characters by the above mechanism is the mark. In particular,(1) and (2) are important characters to control the self-granulatingreaction. In addition, as Examples in the present application, theformation of the shaped particle formed of the amorphous phases(self-granulating reaction particles) is a very specific phenomenon, apart in the present application is based on the finding of thephenomenon and consideration of the control method. In particular, theeffects of the self-granulating reaction of the present invention areparticularly very high when the metal-based structure is theferromagnetic substance containing the metal, or the metal element, as amain component, or is formed of the metal element single phase (Fe).

In addition, from the results of each DSC analysis of the two kinds ofthe self-granulating reaction particles, 10° F. and 300B, it isunderstood that they are both the amorphous single phase structures, butthere is a difference in the amorphous phase structure. It is suggestedthat the results above arise from a cause in which a smaller aggregateforming each particle have a structure different from the other. Inparticular, it is considered that, in Example 1-11, the peak of heatgeneration at a lower temperature side among the two peaks of heatgeneration demonstrates the structure change from the structure formedof the compound or cluster having an m number of 20 (Example 1-11-2) tothe structure formed of that having an m number of 30 (Example 1-11-3).

The detailed mechanism of the self-granulating reaction is unclear, butit is considered that an effect of a surface area, resulting from thespecific uniform size, is one of the factors of self-control. Further,in a case of Examples in the present application, the particles have aspecific magnetism, because they are aggregated and aligned in amagnetic field, and the magnetism is one of the factors of self-control;in other words, there is a possibility in which a magnetically stableshape is formed. It is not observed that the particle size is changeddepending on the presence or absence of a magnetic action, and thus itis considered that the self-control by the magnetic property of theparticle itself may act.

In order to form the shaped particle by itself, i.e., to stably advancethe self-granulating reaction, the “reaction circumstance control” isimportant, and it is preferable that the control is performed so that“the reaction is quietly advanced,” as in Examples in the presentapplication. Further, in order to stably form the shaped particles, orto advance the self-granulating reaction, the formation of thestructure, nanoparticle, or cluster having a specific mix proportion isvery effective. When a compound or a cluster having a mix proportion ofM_(m)H wherein m is an integer and m≥3, or a compound or a clusterhaving a specific m number wherein m≤30, which conforms to the regularpolyhedron rule, in addition to the above, an ordered structure orcompound with a short range is formed by the clusters, theself-granulating reaction is stably advanced due to the specific crystalstructure, composition, and magnetic characteristics of the clusters oraggregates thereof, and shaped particles having the uniform propertiescan be stably and effectively formed, as shown in Examples.

Production (Control) Method

When the concentration (FS) of the reducible substance is controlled asdescribed below, a different H %, m number, shaped particle, compositionand crystal structure can be selectively formed (controlled) When FS(Low range): 0.3≤FS<15, (0.3≤FS<3) mmol/kg is satisfied, an amorphoussingle phase having 0.4 at %≤H %<2.0 at %, an m number≥31, 300B, andFe₂B composition can be obtained. When FS (High range): 3≤FS (preferably150 or less), (preferably 15≤FS≤150) mmol/kg is satisfied, a metal-basedstructure containing Fe amorphous phase, or an Fe amorphous singlephase, having 2.0 at % H %, an m number 30, and 100 F can be obtained.

Further, it is preferable to satisfy the following conditions.

The lower limit:hydrogen-containing substance concentration: H/+>12mmol/kg, FS>0.3 mmol/kg. Further, in order to stably advance theself-granulating reaction, it is preferable that H/+ is less than 2000mmol/kg, FS is less than 150 mmol/kg. Further, in the FS (Low range)above, it is preferable that FS: 0.3 mmol/kg or more and less than 14mmol/kg, and H/+: 6 (NB:3) mmol/kg or more and less than 120 (NB:60)mmol/kg; more preferably that FS: 1.0 mmol/kg or more and less than 3.0mmol/kg, and H/+: 20 (NB:10) mmol/kg or more and less than 120 (NB:60)mmol/kg, in terms of the stable operation.

Further, in the FS (High range) above, it is preferable that (S16) FS:15 mmol/kg or more and less than 150 mmol/kg, H/+: 30 (NB:15) mmol/kg ormore and less than 2000 (NB:1000) mmol/kg, and H: 0.05% by mass (2.7% byatom) or more, more preferably that H: 0.1% by mass (5.3% by atom) ormore, in terms of the stable operation.

Magnetic Field Alignment

When the shaped particles formed by the self-granulating reaction areaggregated and aligned in a magnetic field, a secondary structure can bevery effectively formed because of the uniform property. At that time,the secondary structure can be very effectively formed by the effect ofimproving the adherence, when the H % is the specified value or more,and the amorphous phase is contained.

3-6. Summary of m Number Control A. Method for Controlling m Number

To control the m number is the control of the H %, and thus the m numbercannot be directly controlled by the H concentration during thereaction, for example, the H content in the reaction liquid as in thecase of the control of the H %. In the present application, in view ofthe circumstance, the same indirect control as in the H % control, istried, and it has been found that the m number can be controlled by the“reaction circumstance control” and the “solution control.”

The methods for controlling the m number (operation items andconditions) are as follows:

(1) “solution control”a threshold value of concentration of reducible substance

<Considerations 2 and 5>

(2) “reaction circumstance control”dropwise addition/injection stirringm 20/30 formation of amorphous phase

<Consideration 1>

(3) “solution control”Solvent containing alcoholm 8 reduction of threshold value

<Considerations 3 and 5>

The descriptions of the operation methods and the results have alreadybeen individually made about the H % control, and thus only thedescription about the m number control is made here. As described above,it is understood that the method which is considered to be the indirectcontrol from the viewpoint of the control of the hydrogen content of themetal-based structure is the direct control form the viewpoint of thecontrol of the m number. It is understood that the method is a veryreasonable control method from the viewpoint of the control of the mnumber, and it can be said that it is a phenomenon in which the presenceof the H clusters is demonstrated.

(1) Threshold Value of FS Concentration (Concentration of ReducibleSubstance)

It has been found that m≤30 or less can be obtained at a threshold valueof the FS concentration or more, whereby the H % is controlled to 2.0 at% or more and the metal H clusters are formed. Considering the case ofFe ion in Examples, it is interpreted to be an indirect control that theH % is controlled by the Fe ion concentration, and the H % is increasedby the increase of the Fe ion concentration from the viewpoint of the H%, but it is understood that Fe ion concentration is adjusted to thethreshold value or more, i.e., the Fe ion concentration is adjusted to aspecific value or more, to exclude elements other than Fe and H, wherebythe Fe—H cluster is formed from the viewpoint of the Fe ion, which canbe interpreted to be a direct control. When limiting to the a metal Hcluster having m≤30 or less, there is a positive interrelationshipbetween the FS concentration and the m number, that is, results of(Example 1-7) m=8 at FS_Low, and (Example 1-11) m=20 at FS_High areobtained.

From these results, according to the m number control by the reduciblesubstance concentration, a metal H cluster having m≤30 or less is formedat the threshold value of the reducible substance concentration or more,and when the metal H cluster is formed, a metal H cluster having a largem number can be produced by increasing the concentration of thereducible substance. From the above, the m number control by theconcentration of the reducible substance is interpreted to be the directcontrol. The method for controlling the m number by controlling the FSconcentration, accordingly, has a large effect, in particular, when thereducible substance contains the metal, further when the metal H clusteris formed.

(2) “Reaction Circumstance Control”

By control of a reaction circumstance, i.e., by control of a mixingoperation of (Example 1-11-2) a “dropwise addition” or (Example 1-14) an“injection mixing and stirring” when two liquids were mixed, the mnumbers were respectively controlled to m=20 and m=30. The m number isalso controlled by a heat-treatment different from the “reactioncircumstance control”; that is, the m number was respectively controlledto m=20 and m=30 (Example 1-11-2) before the heat-treatment and (Example1-11-3) after the heat-treatment at 450° C. From DSC analysis results ofm=20 (Example 1-11, FIG. 56), two heat generation peaks are observed,and a heat generation peak at a low temperature side, about 320° C. isinterpreted to be a measurement result demonstrating the structurechange from an H cluster having an m number of 20 to an H cluster havingan m number of 30. From the results, it is interpreted that the Hcluster having an m number of 30 is energetically more stable than the Hcluster having an m number of 20, the H cluster having an m number of20, being at a higher energy level, is formed by “performing quietly”the deposition reaction, and the aggregates thereof form into theamorphous single phase. On the other hand, it is interpreted that the Hcluster having an m number of 30, which is at a lower energy level andis stable, is formed by performing the “injection mixing and stirring”or the heat-treatment at 450° C. A mechanism in which the H clusterhaving an m number of 30, or the metal-based structure, which isaggregates of the clusters, forms an amorphous phase partly containingcrystal phases, is not clear, but it is considered that the mixproportion of the metal atom is increased by increasing the m number,and formation of crystal structure formed of the metal atom is appeared.Since the result of partly containing the crystal phases, it is alsointerpreted that the H cluster having an m of 30 is a more stablecluster at a lower energy level or forms a more stably assembledstructure.

(3) Solvent

In Examples, it was found that the effect of decreasing the thresholdvalue of the concentration of the reducible substance is expressed bycontaining ethanol in the solvent. The threshold value is aconcentration value or more at which the metal H cluster can be formed,it is considered that in Examples, the presence of ethanol increases thebinding reactivity of Fe—H, and the metal H cluster is easily formedprior to reactions with other elements, and as a result, the metal Hcluster can be formed at a lower concentration of the reduciblesubstance, i.e., the effect of decreasing the threshold value isappeared. It is understood that the metal H cluster can be formed at alow concentration of the reducible substance by the presence of ethanol,as a result, the metal H cluster having a low content ratio of the metalatoms (the m number is small), i.e., having a large H %, is formed.

B. Phenomenon (Physical Property) Controlled by m Number

The following items are controlled by controlling the m number (physicalproperty control by selection of cluster)

(i) H % control: m number <all Examples, measured H %>(ii) Composition control: metal H cluster (m≥30) <Consideration 5>(iii) Amorphous phase control: amorphous single phase (m≥20) at metal Hcluster <Consideration 1>(iv) Particle shape control: particles by self-granulating reaction(m≥8), formless phase (m≤12) <Considerations 2 and 3>

(i) H % Control

The H % (at %) is decided by the m number, i.e., the mix proportion.

(ii) Composition Control

An H cluster containing the metal-based element, or metal element isformed at an m number more than 3. A “metal H cluster” formed of metalelement, or the metal single element is formed at m≤30; that is, thecomposition of the metal-based element is controlled. In Examples,structures, nanoparticles, or cluster, having an Fe₂B composition,formed of the metal and the semi-metal, and containing the metalelement, were formed at m≥31. Structures, nanoparticles, or cluster,formed of the metal element or the single element metal (Fe), wereformed at m≤30.

(iii) Amorphous Phase Control

In the “metal H cluster” having m≤30, the crystal structure or theamorphous structure is controlled by the m number. In Examples, anamorphous phase is formed at m≤30. A partly crystallized amorphousphase-containing structure is obtained at m=30. An amorphous singlephase is formed at m≤20. There is a case in which the amorphousstructure varies depending on the m number even if they have the sameamorphous single phase structure. In Examples (comparison of Example1-11-2 and 1-7), because there is a difference in DSC analysis results(FIG. 56/FIG. 54) between the case of m=20 and the case of m=8, althoughin both cases the amorphous single phase is formed, the difference inthe amorphous structure is confirmed. It is considered that thedifference in the amorphous structure is caused by the difference in them number, i.e., the difference in the cluster structure.

(iv) Particle Shape Control (Shaped/Formless)

There is a case in which the shaped particle formation is controlled bythe m number. It is particularly preferable that the shaped particlesare formed by the self-granulating reaction. In Examples, shapedparticles were formed by the self-granulating reaction at m≥8, and aformless phase formed of the amorphous phase was formed at m≤12 furtherat m≤8. A transitive state in which the shaped particles and theformless phases are mixed was obtained at m=8. Further, the shapedparticles may sometimes be controlled by the m number. In Examples(Example 1-7), self-granulating reaction particles having a particlesize of 500 nm or less and formed of the amorphous single phase wereobtained at m≥8. Further, (Example 1-11-2) self-granulating reactionparticles having a particle length of less than 175 nm and formed of theamorphous single phase were obtained at m≥12, further at m≥20. Althoughthese self-granulating reaction particles are both has the amorphoussingle phase structure, since there is a difference in DSC analysisresults (FIG. 54/FIG. 56), the difference in the amorphous phasestructure is confirmed. It is considered that the difference in theamorphous structure is caused by the m number, i.e., the difference inthe cluster structure.

What is claimed is:
 1. A method for producing a metal-based structure, the method comprising: reducing, in liquid, a reducible substance containing a metal-based reducible component wherein the metal-based reducible component contains at least one metal element and/or semi-metal element, wherein the metal-based structure corresponds to at least one of the following (I) to (III): (I) the metal-based structure, wherein the method further comprises a step of controlling at least one of the following (i) to (iii) by controlling a hydrogen content based on the whole amount of the metal-based structure, the hydrogen being contained in the metal-based structure: (i) controlling formation of an amorphous phase which the metal-based structure comprises; (ii) controlling a particle shape of the metal-based structure; and (iii) controlling a composition of the metal-based structure, (II) the metal-based structure comprising a hydrogen compound, a cluster, or an aggregate thereof comprising M and H, which is represented by the general formula: M_(m)H, wherein: m is an integer of 6 or more and 300 or less, M represents one or more metals or a mixture of one or more metals and one or more semi-metals, and H is a hydrogen atom, (III) the metal-based structure comprising the hydrogen compound, the cluster, or the aggregate thereof comprising M and H, and further comprising an amorphous phase at least in part, wherein: M represents one or more metals or a mixture of one or more metals and one or more semi-metals, and H is a hydrogen atom.
 2. The metal-based structure according to claim 1, further comprising a metal-based amorphous phase which is amorphized by containing hydrogen.
 3. The method for producing a metal-based structure according to claim 1, wherein: the hydrogen content is controlled to 0.41% by atom or more, thereby to form the metal-based structure comprising a metal-based amorphous phase, and/or the hydrogen content is controlled to 2.0% by atom or more, thereby to form the metal-based structure comprising the metal-based amorphous phase wherein the metal-based amorphous phase comprises a metal element as a main component, and/or the hydrogen content is controlled to 3.3% by atom or more, thereby to form the metal-based structure substantially comprising the metal-based amorphous phase alone wherein the metal-based amorphous phase comprises a metal element as a main component, and/or the hydrogen content is controlled to 5.5% by atom or more, thereby to form the metal-based structure substantially comprising a metal-based amorphous phase alone wherein the metal-based amorphous phase comprises a metal element as a main component and at least a part of the metal-based amorphous phase is formless.
 4. The method for producing a metal-based structure according to claim 1, wherein the A % by atom, which is the hydrogen content, is controlled to a value satisfying the following formulae (1) and (2) based on the whole amount of the metal-based structure: Y=100×1/(X+1) wherein X=4,6,8,12,20, or 30  (1), 0.85Y≤A≤1.15Y  (2).
 5. The method for producing a metal-based structure according to claim 1, the method comprising a step of: controlling the m to 30 or less, whereby the metal-based structure comprises a metal element as a main component, and/or controlling the m to 31 or more, whereby the metal-based structure comprises a metal as a main component.
 6. The method for producing a metal-based structure according to claim 1, the method comprising a step of: controlling the m to 31 or more, thereby to form the metal-based structure comprising a metal-based amorphous phase, and/or controlling the m to 30 or less, thereby to form the metal-based structure comprising the metal-based amorphous phase wherein the metal-based amorphous phase comprises a metal element as a main component, and/or controlling the m to 20 or less, thereby to form the metal-based structure substantially comprising the metal-based amorphous phase alone wherein the metal-based amorphous phase comprises a metal element as a main component, and/or controlling the m to 12 or less, thereby to form the metal-based structure substantially comprising the metal-based amorphous phase alone wherein the metal-based amorphous phase comprises a metal element as a main component and at least a part of the metal-based amorphous phase is formless.
 7. The method for producing a metal-based structure according to claim 1, wherein at least a part of hydrogen contained in the metal-based structure are non-diffusible hydrogen contained in the metal-based structure after the metal-based structure is heated at 200° C. for 2 minutes.
 8. The method for producing a metal-based structure according to claim 1, which contains hydrogen, comprising a step of a reduction step which comprises reducing a reducible substance containing at least one of a metal element and/or a semi-metal element in liquid containing at least one of hydrogen and a hydrogen-containing substance, wherein at least a part of the hydrogen are non-diffusible hydrogen contained in the metal-based structure after the metal-based structure is heated at 200° C. for 2 minutes.
 9. The method for producing a metal-based structure according to claim 1, wherein the reduction step comprises a step in which a solution A which contains a reducible substance containing at least one of a metal element and/or a semi-metal element and a solution B which contains at least one of hydrogen and a hydrogen-containing substance, and has a reducing action are mixed to form mixed liquid.
 10. The method for producing a metal-based structure according to claim 9, which further comprises a step in which a magnetic field is applied to the mixed liquid, thereby to control a shape anisotropy of the metal-based structure.
 11. The method for producing a metal-based structure according to claim 1, comprising a step of heating and/or pressurizing the metal-based structure, thereby to decrease a volume of a cavity in the metal-based structure, to stick the metal-based structures to each other, to stick part structures in the metal-based structure to each other, and/or to stick an additional substance to the metal-based structure.
 12. The method for producing a metal-based structure according to claim 1, comprising a step of heating the metal-based structure and/or decreasing the hydrogen content of the metal-based structure, thereby to form a crystal phase at least in part.
 13. A method for producing a composite structure, comprising: the method for producing the metal-based structure according to claim 1; and adding at least one additional substance.
 14. The method for producing a composite structure according to claim 13, comprising a step of heating the metal-based structure and/or decreasing the hydrogen content of the metal-based structure, thereby to form a crystal phase at least in part. 